Perry has 4 more 20-cent coins than 5-cent coins. After he used 13 of his 20-cent coins, the total value of 20-cent coins is $2.70 more than the total value of 5-cent coins. How many coins did he have in the end?

	20¢	5¢
Before	1 u + 4	1 u
Change	- 13
After	1 u - 9	1 u

	20¢	5¢
Number	1 u - 9	1 u
Value	20	5
Total value	20 u - 180	5 u

$1 = 100¢
$2.70 = 270¢

Number of 20¢ coins in the end
= 1 u + 4 - 13
= 1 u - 9

Total value of 20¢ coins in the end
= 20 x (1 u - 9)
= 20 u - 180

Total value of 5¢ coins in the end
= 5 x 1 u
= 5 u

After using 13 20-cent coins, the value of 20-cent coins is 270¢ more than the value of 5-cent coins. If another 270¢ is added to the 5-cent coins, the total value of 20-cent coins and 5-cent coins will be the same.

20 u - 180 = 5 u + 270
20 u - 5 u = 270 + 180
15 u = 450

1 u = 450 ÷ 15 = 30

Number of coins that Perry had in the end
= 1 u + 1 u - 9
= 2 u - 9
= (2 x 30) - 9
= 60 - 9
= 51

Answer(s): 51