During a donation drive, $2180 was collected by 80 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 |
80
|
80 x 30 =
$2400 |
0 |
0
|
$2400 |
79
|
79 x 30 =
$2370 |
1 |
1 x 20 =
$20 |
$2390 |
58
|
58 x 30 =
$1740 |
22
|
22 x 20 =
$440 |
$2180
|
Total amount collected if all the donations were made by boys
= 80 x 30
= $2400
Big difference in the total amounts made between the boys and the girls
= 2400 - 2180
= $220
Small difference in the amount made between one boy and one girl
= 30 - 20
= $10
Number of girls
= 220 ÷ 10
= 22
Number of boys
= 80 - 22
= 58
Answer(s): 58
