In a basketball freethrow contest, a man gets a dime every time he makes a basket, and pays a quarter for each missed shot. If he takes 100 shots and wins $5.10, how many times did he miss?
Let x = number of times he missed the shot. (costing him 25 cents per shot missed)
Then 100 - x = number of times that he made a basket. (gaining him 10 cents per shot made)
0.10(100 - x) - 0.25(x) = 5.10
10.00 - 0.10x - 0.25x = 5.10
10.00 - 0.35x = 5.10
-0.35x = -.90
x = 14 <--- number of shots missed.