There were a total of thirty-six 20-cent coins and 50-cent coins in a bag. Given that the total amount of money in the bag was $12.60. How many 20-cent coins were there in the bag?
Number of
50-cent coins |
Value of
50-cent coins |
Number of
20-cent coins |
Value of
20-cent coins |
Total
value |
36
|
36 x 50
= 1800¢ |
0
|
0
|
1800¢
|
35
|
35 x 50
= 1750¢ |
1
|
1 x 20
= 20¢ |
1770¢
|
18
|
18 x 50
= 900¢ |
18
|
18 x 20
= 360¢ |
1260¢ |
$1 = 100¢
$12.60 = 1260¢
Amount in the bag if all are 50-cent coins
= 36 x 50
= 1800¢
Big difference between the value of 50-cent coins and 20-cent coins
= 1800 - 1260
= 540¢
Small difference between the value of one 50-cent coin and one 20-cent coin
= 50 - 20
= 30¢
Number of 20-cent coins
= 540 ÷ 30
= 18
Answer(s): 18
