1. Problem: Find the following percentages of given quantities. 2. Formula: To find $x\%$ of a number $N$, use the formula: $$\text{Percentage value} = \frac{x}{100} \times N$$ 3. Important rule: Convert mixed fractions to improper fractions before calculating. 4. Calculations: (i) 10% of 18000: $$= \frac{10}{100} \times 18000 = 0.1 \times 18000 = 1800$$ (ii) 4% of 52: $$= \frac{4}{100} \times 52 = 0.04 \times 52 = 2.08$$ (iii) 3 \frac{2}{5} \% = \frac{17}{5} \% = \frac{17}{5} \times \frac{1}{100} = \frac{17}{500}$$ So, $$= \frac{17}{500} \times 60 = \frac{17 \times 60}{500} = \frac{1020}{500} = 2.04$$ (iv) 4 \frac{1}{5} \% = \frac{21}{5} \% = \frac{21}{500}$$ So, $$= \frac{21}{500} \times 700 = \frac{21 \times 700}{500} = \frac{14700}{500} = 29.4$$ (v) 3% of 7000: $$= \frac{3}{100} \times 7000 = 0.03 \times 7000 = 210$$ (vi) 20% of 15: $$= \frac{20}{100} \times 15 = 0.2 \times 15 = 3$$ Final answers: (i) 1800 (ii) 2.08 (iii) 2.04 km (iv) 29.4 l (v) 210 kg (vi) 3 days