During a donation drive, $2910 was collected by 80 students. Each girl donated $40 and each boy donated $30. How many girls were there?
Number of girls |
Amount collected by girls |
Number of boys |
Amount collected by boys |
Total amount collected |
80
|
80 x 40 = $3200 |
0 |
0
|
$3200 |
79
|
79 x 40 = $3160 |
1 |
1 x 30 = $30 |
$3190 |
51
|
51 x 40 = $2040 |
29
|
29 x 30 = $870 |
$2910
|
Total amount collected if all the donations were made by girls
= 80 x 40
= $3200
Big difference in the total amounts made between the girls and the boys
= 3200 - 2910
= $290
Small difference in the amount made between one girl and one boy
= 40 - 30
= $10
Number of boys
= 290 ÷ 10
= 29
Number of girls
= 80 - 29
= 51
Answer(s): 51