During a donation drive, $680 was collected by 50 students. 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 |
50
|
50 x 20 =
$1000 |
0 |
0
|
$1000 |
49
|
49 x 20 =
$980 |
1 |
1 x 10 =
$10 |
$990 |
18
|
18 x 20 =
$360 |
32
|
32 x 10 =
$320 |
$680
|
Total amount collected if all the donations were made by girls
= 50 x 20
= $1000
Big difference in the total amounts made between the girls and the boys
= 1000 - 680
= $320
Small difference in the amount made between one girl and one boy
= 20 - 10
= $10
Number of boys
= 320 ÷ 10
= 32
Number of girls
= 50 - 32
= 18
Answer(s): 18
