1. **Problem Statement:** 15. A sum of money is divided among Albert, Brian and Chrissy in ratio 3:5:7. Chrissy's share is 3500. 17. An alloy consists of steel, silver and copper in the ratio 6:5:9. The smallest mass is 160 g, find the mass of the copper. --- 2. **Solve 15(a): Total sum of money** - The parts of the ratio are 3 + 5 + 7 = 15 parts total. - Chrissy's share corresponds to 7 parts and equals 3500. - One part = $\frac{3500}{7} = 500$ - Total sum = $15 \times 500 = 7500$ 3. **Solve 15(b): Brian's share** - Brian's share is 5 parts. - Brian's share = $5 \times 500 = 2500$ 4. **Solve 15(c): Percentage of total Albert receives** - Albert's share is 3 parts = $3 \times 500 = 1500$ - Percentage Albert receives = $\frac{1500}{7500} \times 100 = 20\%$ --- 5. **Solve 17: Copper mass in alloy** - Ratio given: Steel : Silver : Copper = 6 : 5 : 9 - Smallest mass among these is 160 g, corresponding to the smallest ratio number. - Smallest ratio number is 5 (Silver), so mass of silver corresponds to 160 g. - Find the multiplier $k$ for ratio: $5k = 160 \Rightarrow k = \frac{160}{5} = 32$ - Copper mass = $9k = 9 \times 32 = 288$ g --- **Final answers:** - 15(a) Total sum: 7500 - 15(b) Brian's share: 2500 - 15(c) Albert's percentage: 20% - 17 Copper mass: 288 g