During a donation drive, $1110 was collected by 50 pupils. Each girl donated $30 and each boy donated $20. 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 30 =
$1500 |
0 |
0
|
$1500 |
49
|
49 x 30 =
$1470 |
1 |
1 x 20 =
$20 |
$1490 |
11
|
11 x 30 =
$330 |
39
|
39 x 20 =
$780 |
$1110
|
Total amount collected if all the donations were made by girls
= 50 x 30
= $1500
Big difference in the total amounts made between the girls and the boys
= 1500 - 1110
= $390
Small difference in the amount made between one girl and one boy
= 30 - 20
= $10
Number of boys
= 390 ÷ 10
= 39
Number of girls
= 50 - 39
= 11
Answer(s): 11
