math
posted by Anonymous .
Bobby has only pennies, dimes, and quarters. One half of Bobby's coins are pennies. One fourth of coins are quarters. Three of his coins are dimes. How many coins does Bobby have?

Let x = total number of coins.
1/2x + 1/4x + 3 = x
3 = x  3/5x
3 = 1/4x
3 / (1/4) = x
3 * 4 = x
12 = x 
let the number of coins he has be x
x/2 + x/4 + 3 = x
times 8
4x + 2x + 24 = 8x
2x = 24
x = 12
12/2 = 6 pennies
12/4 = 3 quarters
+ 3 dimes
= 12 coins
(A better question would have been:
How much money does Bobby have with his coins? )