#### 3.13 Problem 13: Price of the Ball

Things are not as they seems to be at first glance, sit down and calculate! Let
x be the price of a golf club, and let y be the price of the ball. Together they
cost 110, hence x + y = 110. The difference is 10, that means: x - y = 10.
Now its is easy to see that x = 105 and y = 5. The price of the ball is 5
=C(and not 10 = C).