Since the girl scout sold 5 more boxes on the second week, we have (x + 5) number of boxes sold for the second week. Now, for the third week, since it's double that of the second week, we have 2(x + 5). Thus, we have the following:
first week: x
second week: x + 5
third week: 2(x + 5)
Given that the total number of boxes sold for the three weeks is 431. We have
x + (x + 5) + 2(x + 5) = 431
x + x + 5 + 2x + 10 = 431
4x + 15 = 431
4x = 431 - 15
4x = 416
x = 104
We have now the value of x. Using this, we can find the values for the second and third week.
x + 5 = `104 + 5 = 109
2(x + 5) = 2(109) = 218
Answer:
first week: 104
second week: 109
third week: 218
