Answer: 10
Explanation:
A. 2.50 + 2.50 + 2.50 + 2.50
the sum of 2.50, 4 times
B. The sum is 10, Maila's friends tell her to sell each wristband for 2.50. And 4 were bought, so add 2.50+2.50+2.50+2.50.
10 9 8 7 6 5 4 3 2 1 0
---0----|----|--•--|----|----•----|----|--•--|----|---
<----------- <---------- <----------- <------
+ + + +
2.50 2.50 2.50 2.50