The number of ten-cent coins in a jar was
13 the number of twenty-cent coins. Eric took out 19 twenty-cent coins and exchanged them for ten-cent coins. Then he put the money back into the jar. The number of twenty-cent coins became
58 the number of ten-cent coins. How much money was there in the jar?
|
Make u the same (1)x3 = (3) |
10-cent (1) |
20-cent (2) |
Before |
3 u |
1 u |
3 u |
Change |
+ 114 |
+ 38 |
- 19 |
After |
24 p |
8 p |
5 p |
Value of 20-cent coins to be exchanged to 10-cent coins
= 19 x 20
= 380
Number of 10-cent coins to be exchanged from the 20-cent coins
= 380 ÷ 10
= 38
(3) = (2)
24 p - 114 = 5 p + 19
24 p - 5 p = 19 + 114
19 p = 133
1 p = 133 ÷ 19 = 7
Number of 10-cent coins in the end
= 8 p
= 8 p x 7
= 56
Value of 10-cent coins in the end
= 56 x 10
= 560¢
Number of 20-cent coins in the end
= 5 p
= 5 x 7
= 35
Value of 20-cent coins in the end
= 35 x 20
= 700¢
Total value of coins
= 560 + 700
= 1260¢
$1 = 100¢
1260¢ = $12.60
Answer(s): $12.60