Algebra
posted by Garrett .
I have only dimes, nickels, and pennies in my wallet. Seven of the coins are dimes, 25 percent are nickels and 5/9 of them are pennies. How many coins do I have?

let the total be x
7 + x/4 + (5/9)x = x
times 36
252 + 9x + 20x = 36x
252 = 7x
x = 36
You have 36 coins
check:
(1/4)(36) = 9 nickels
(5/9)(36) = 20 pennies
dimes = 7
total = 7+9+20 = 36