Question

A girl scout troop sold cookies. If the girls sold 5 more boxes the second week than they did the first, and if they doubled the sales of the second week for the third week to sell a total of 431 boxes of cookies, how many did they sell each week? They sold a0 boxes the first week, a1 boxes the second week, and a2 boxes the third week

Answer 1

• 104 boxes the first week
• 109 boxes the second week
• 218 boxes the third week

Explanation:

Let s represent the first week's sales. Then the second week's sales were 5 more, or (s+5). The third week's sales were double the second week, so were 2(s+5).

Total sales for the 3 weeks were 431 boxes, so we have ...

s + (s +5) + 2(s +5) = 431

4s + 15 = 431 . . . . collect terms

4s = 416 . . . . . . . . subtract 15

s = 104 . . . . . . . . . .divide by 4

(s+5) = 109

2(s+5) = 218

The troop sold ...

• 104 boxes the first week
• 109 boxes the second week
• 218 boxes the third week