During a donation drive, $1410 was collected by 60 pupils. Each boy donated $30 and each girl donated $20. How many boys were there?
Number of boys |
Amount collected by boys |
Number of girls |
Amount collected by girls |
Total amount collected |
60
|
60 x 30 = $1800 |
0 |
0
|
$1800 |
59
|
59 x 30 = $1770 |
1 |
1 x 20 = $20 |
$1790 |
21
|
21 x 30 = $630 |
39
|
39 x 20 = $780 |
$1410
|
Total amount collected if all the donations were made by boys
= 60 x 30
= $1800
Big difference in the total amounts made between the boys and the girls
= 1800 - 1410
= $390
Small difference in the amount made between one boy and one girl
= 30 - 20
= $10
Number of girls
= 390 ÷ 10
= 39
Number of boys
= 60 - 39
= 21
Answer(s): 21