There were a total of fifty 10-cent coins and 20-cent coins in a bag. Given that the total amount of money in the bag was $8.10. How many 10-cent coins were there in the bag?
Number of 20-cent coins |
Value of 20-cent coins |
Number of 10-cent coins |
Value of 10-cent coins |
Total value |
50
|
50 x 20 = 1000¢ |
0
|
0
|
1000¢
|
49
|
49 x 20 = 980¢ |
1
|
1 x 10 = 10¢ |
990¢
|
31
|
31 x 20 = 620¢ |
19
|
19 x 10 = 190¢ |
810¢ |
$1 = 100¢
$8.10 = 810¢
Amount in the bag if all are 20-cent coins
= 50 x 20
= 1000¢
Big difference between the value of 20-cent coins and 10-cent coins
= 1000 - 810
= 190¢
Small difference between the value of one 20-cent coin and one 10-cent coin
= 20 - 10
= 10¢
Number of 10-cent coins
= 190 ÷ 10
= 19
Answer(s): 19