During a donation drive, $1680 was collected by 80 pupils. Each girl donated $30 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 |
80
|
80 x 30 =
$2400 |
0 |
0
|
$2400 |
79
|
79 x 30 =
$2370 |
1 |
1 x 10 =
$10 |
$2380 |
44
|
44 x 30 =
$1320 |
36
|
36 x 10 =
$360 |
$1680
|
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 - 1680
= $720
Small difference in the amount made between one girl and one boy
= 30 - 10
= $20
Number of boys
= 720 ÷ 20
= 36
Number of girls
= 80 - 36
= 44
Answer(s): 44
