During a donation drive, $830 was collected by 60 pupils. Each girl donated $20 and each boy donated $10. How many girls were there?
Number of girls |
Amount collected by girls |
Number of boys |
Amount collected by boys |
Total amount collected |
60
|
60 x 20 = $1200 |
0 |
0
|
$1200 |
59
|
59 x 20 = $1180 |
1 |
1 x 10 = $10 |
$1190 |
23
|
23 x 20 = $460 |
37
|
37 x 10 = $370 |
$830
|
Total amount collected if all the donations were made by girls
= 60 x 20
= $1200
Big difference in the total amounts made between the girls and the boys
= 1200 - 830
= $370
Small difference in the amount made between one girl and one boy
= 20 - 10
= $10
Number of boys
= 370 ÷ 10
= 37
Number of girls
= 60 - 37
= 23
Answer(s): 23