Solve question no. 3 of page no. 84 from the chapter "Average" of textbook "Shaping Maths AB 5B Part I - Solutions".
2 $50.40 = $100.8
The total cost of Siti and Xinmin's shoes is $100.8.
4 units = $100.8
| 1 unit | = | $100.8 4 |
| = | $25.2 |
| 3 units | = | 3 $25.2 |
| = | $75.6 |
The cost of Siti's shoes is $75.6.