1. Problem (d): Calculate $\frac{2}{3} \times \left(1 \frac{1}{4} - \frac{5}{8}\right)$.\n 2. Convert mixed number to improper fraction: $1 \frac{1}{4} = \frac{5}{4}$.\n 3. Find the difference inside the parentheses: $$\frac{5}{4} - \frac{5}{8} = \frac{10}{8} - \frac{5}{8} = \frac{5}{8}.$$\n 4. Multiply by $\frac{2}{3}$: $$\frac{2}{3} \times \frac{5}{8} = \frac{10}{24} = \frac{5}{12}.$$\n 5. Final answer: $\boxed{\frac{5}{12}}$.\n\n6. Problem 8: Tank capacity problem.\n7. Let tank capacity be $x$ litres. Initially, tank has $\frac{9}{13}x$ litres.\n8. After removing 300 litres, water amount is $\frac{9}{13}x - 300$. Given this equals $\frac{11}{17}x$.\n9. Set equation: $$\frac{9}{13}x - 300 = \frac{11}{17}x.$$\n 10. Rearranged: $$\frac{9}{13}x - \frac{11}{17}x = 300.$$\n 11. Find common denominator of 13 and 17 is 221, rewrite: $$\frac{153}{221}x - \frac{143}{221}x = 300 \Rightarrow \frac{10}{221}x = 300.$$\n 12. Solve for $x$: $$x = 300 \times \frac{221}{10} = 6630.$$\n 13. Final answer: Tank capacity is $\boxed{6630}$ litres.\n\n14. Problem 9(a): Find next number in the pattern $1\frac{1}{8}, 1\frac{1}{2}, 1\frac{7}{8}, \ldots$.\n15. Convert to improper fractions: $1\frac{1}{8}=\frac{9}{8}$, $1\frac{1}{2}=\frac{3}{2}=\frac{12}{8}$, $1\frac{7}{8} = \frac{15}{8}$.\n16. Differences: $\frac{12}{8} - \frac{9}{8} = \frac{3}{8}$ and $\frac{15}{8} - \frac{12}{8} = \frac{3}{8}$.\n17. Pattern increases by $\frac{3}{8}$ each time. Next term: $\frac{15}{8} + \frac{3}{8} = \frac{18}{8} = 2\frac{2}{4} = 2\frac{1}{4}$.\n\n18. Problem 9(b): Pattern $\frac{1}{2}, 1\frac{1}{2}, 4\frac{1}{2}, 13\frac{1}{2}, \ldots$.\n19. Convert to improper fractions: $\frac{1}{2}$, $\frac{3}{2}$, $\frac{9}{2}$, $\frac{27}{2}$.\n20. Pattern multiplies by 3 each time: $\frac{1}{2} \times 3 = \frac{3}{2}$, $\frac{3}{2} \times 3 = \frac{9}{2}$, $\frac{9}{2} \times 3 = \frac{27}{2}$.\n21. Next number: $\frac{27}{2} \times 3 = \frac{81}{2} = 40\frac{1}{2}$.\n\n22. Problem 10: Kirimi's salary problem.\n23. Let salary be $S$. Rent: $\frac{1}{2}S$, remainder: $S - \frac{1}{2}S=\frac{1}{2}S$.\n24. Entertainment: $\frac{1}{3}$ of remainder $= \frac{1}{3} \times \frac{1}{2}S = \frac{1}{6}S$.\n25. Food expenses = remainder after entertainment: $$\frac{1}{2}S - \frac{1}{6}S = \frac{3}{6}S - \frac{1}{6}S = \frac{2}{6}S=\frac{1}{3}S.$$\n26. Given food expense = 36000, so: $$\frac{1}{3}S=36000 \Rightarrow S=36000 \times 3=108000.$$\n27. Kirimi's salary is $\boxed{108000}$.\n\n28. Problem 11: Animal fractions.\n29. Cows: $\frac{1}{8}$, goats: $\frac{1}{3}$. Others: $1 - \frac{1}{8} - \frac{1}{3} = 1 - \frac{3}{24} - \frac{8}{24} = 1 - \frac{11}{24} = \frac{13}{24}$.\n30. Sheep: half of remainder $= \frac{1}{2} \times \frac{13}{24} = \frac{13}{48}$.\n31. Camels: remainder after sheep $= \frac{13}{24} - \frac{13}{48} = \frac{26}{48} - \frac{13}{48} = \frac{13}{48}$.\n32. Fraction of camels is $\boxed{\frac{13}{48}}$.\n\n33. Problem 12: Votes.\n34. Given fractions add to more than 1, so must interpret question carefully. Since votes cannot exceed 1, compatible fractions need review. Check sum of B, C, D: $\frac{2}{5} + \frac{7}{10} + \frac{1}{3} = \frac{4}{10} + \frac{7}{10} + \frac{10}{30} = 1.1 + 0.333... >1$.\n35. Assuming problem has a misprint or recount; skipping detailed solution due to inconsistency.\n 36. Problem Exercise 2.1 (a): Convert $\frac{17}{25}$ to decimal.\n37. Division: $\frac{17}{25}=0.68$.\n 38. Exercise 2.1 (b): $1 \frac{3}{8} = 1 + 0.375 = 1.375$.\n 39. Exercise 2.1 (c): $\frac{3}{40} = 0.075$.\n 40. Exercise 2.2 (a): Convert recurring decimal $0.27$ to fraction. As no repetition indication, interpreting as 0.27 (terminating) = $\frac{27}{100}$.\n 41. Exercise 2.2 (b): $0.083$ similarly $\frac{83}{1000}$.\n 42. Exercise 2.2 (c): $0.09 = \frac{9}{100}$.\n 43. Exercise 2.2 (d): $5.16= \frac{516}{100} = \frac{129}{25}$.\n 44. Problem 2.3 rounding examples provided.\n 45. Problem 2.4 express 6395 to one significant figure: $\boxed{6000}$.\n 46. Problem 2.5 express 0.09052 to two significant figures: $\boxed{0.091}$.\n 47. Problem 2.6: number of significant figures: (a) 13.18405 is 7, (b) 8.30 is 3, (c) 9000 ambiguous without context but usually 1 unless specified.\n 48. Problem 2.7 convert to standard form: (a) 0.00475=$4.75 \times 10^{-3}$, (b) 87593=$8.7593 \times 10^{4}$, (c) 6.9=$6.9 \times 10^{0}$.\n 49. Problem 2.8 (a) $6.12 \times 10^{-3} = 0.00612$, (b) $4.03 \times 505 = 2035.15$.\n 50. Problem 2.9 (a): Calculate $0.2 \times 0.17 \times 3.5 \div 0.05 \times 20$. Simplify stepwise:\n $0.2 \times 0.17 = 0.034$,\n $0.034 \times 3.5 = 0.119$,\n $0.119 \div 0.05 = 2.38$,\n $2.38 \times 20 = 47.6$.\n 51. Problem 2.9 (b): $1.35 + 0.3 + 0.4 \times 0.2 \div 0.02$. Evaluate multiplication and division first: $0.4 \times 0.2 = 0.08$, $0.08 \div 0.02 = 4$. Sum: $1.35 + 0.3 + 4 = 5.65$.\n 52. Problem 2.10: Party attendance. Let total people be $x$. Soda takers: $0.6x$. Remaining: $0.4x$. Milk takers: $0.5 \times 0.4x = 0.2x$. Orange juice takers: $0.4x - 0.2x = 0.2x$. Given 48 took orange juice, so $0.2x=48$, thus $x=240$.\n 53. Problem 3.1 (a): Calculate $(4.613)^2$. Using approximation or calculator: $4.613^2 \approx 21.28$.\n Final answers summarized for clarity in each problem as boxed above.