Define x:
Let the cost of the ball be x.
Ball = x
Bat = x + 0.1
The total cost is $1.10:
x + x + 0.1 = 1.1
2x + 0.1 = 1.1
2x = 1
x = 0.5
Find the cost of the bat and the ball:
ball = x = $0.50
bat = x + 0.1 = 0.5 + 0.1 = $0.60
Answer: The ball cost $0.50