Jar Q contains 20-cent coins and Jar R contains 10-cent coins. There are 13 more coins in Jar R than in Jar Q. The amount of money in Jar Q is 40¢ more than the amount of money in Jar R. How many total coins are there?
| |
Jar Q |
Jar R |
| Number |
1 u |
1 u + 13 |
| Value |
20¢ |
10¢ |
| Total value |
20 u |
10 u + 130 |
Total value of 20¢ coins in Jar Q
= 20 x 1 u
= 20 u
Total value of 10¢ coins in Jar R
= 10 x (1 u + 13)
= 10 u + 130
The amount in Jar Q is 40¢ more than Jar R. If another 40¢ is added into Jar R, both Jar Q and Jar R will have the same amounts of money.
20 u = 10 u + 130 + 40
20 u - 10 u = 130 + 40
10 u = 170
1 u = 170 ÷ 10 = 17
Total number of coins
= 1 u + (1 u + 13)
= 2 u + 13
= 2 x 17 + 13
= 34 + 13
= 47
Answer(s): 47
