Answer and Explanation:
The computation is shown below;
a. Rate of return
= (Selling price - purchase price) ÷ (purchase price × margin)
= ($17.50 - $10) ÷ ($10 × 25%)
= $7.50 ÷ 2.50
= 300%
b. Rate of return
= (Selling price - purchase price) ÷ (purchase price × margin)
= ($17.50 - $10) ÷ ($10 × 50%)
= $7.50 ÷ 5
= 150%
c. Rate of return
= (Selling price - purchase price) ÷ (purchase price × margin)
= ($17.50 - $10) ÷ ($10 × 75%)
= $7.50 ÷ 7.50
= 100%