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
