During a donation drive, $2200 was collected by 80 students. Each girl donated $30 and each boy donated $20. 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 30 = $2400 |
0 |
0
|
$2400 |
79
|
79 x 30 = $2370 |
1 |
1 x 20 = $20 |
$2390 |
60
|
60 x 30 = $1800 |
20
|
20 x 20 = $400 |
$2200
|
Total amount collected if all the donations were made by girls
= 80 x 30
= $2400
Big difference in the total amounts made between the girls and the boys
= 2400 - 2200
= $200
Small difference in the amount made between one girl and one boy
= 30 - 20
= $10
Number of boys
= 200 ÷ 10
= 20
Number of girls
= 80 - 20
= 60
Answer(s): 60