During a donation drive, $1220 was collected by 60 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 |
60
|
60 x 30 =
$1800 |
0 |
0
|
$1800 |
59
|
59 x 30 =
$1770 |
1 |
1 x 10 =
$10 |
$1780 |
31
|
31 x 30 =
$930 |
29
|
29 x 10 =
$290 |
$1220
|
Total amount collected if all the donations were made by girls
= 60 x 30
= $1800
Big difference in the total amounts made between the girls and the boys
= 1800 - 1220
= $580
Small difference in the amount made between one girl and one boy
= 30 - 10
= $20
Number of boys
= 580 ÷ 20
= 29
Number of girls
= 60 - 29
= 31
Answer(s): 31
