Ed has x dimes and y quarters, totaling 24 coins. x + y = 24
Ed has $3.60. 360 = 10x +25y
x + y = 24
subtract y from both sides
x = 24 - y
substitute for x in the other equation
360 = 10x + 25y
360 = 10*(24-y) + 25y
solve for y
360 = 240 -10y + 25y
360 = 240 + 15y
120 = 15y
8 = y
solve for x
x + y = 24
x + 8 = 24
x = 16
Ed has 16 dimes ($1.60) and 8 quarters ($2.00) totaling $3.60.