> The ball costs $0.10. Let's prove this using an equation. {uses equation}. The ball costs $0.10.

> The bat costs $1 more than the ball, so the bat costs $1 + x, where x is the cost of the ball. The bat and the ball together cost $1.10, so the cost of the ball is $1.10 - $1 - x = $0.10 - x. Since the bat costs $1 + x, we know that $1.10 = $1 + x + $0.10 - x = $1 + $0.10. Therefore, the cost of the ball is $0.10 - x = $0.10 - ($1.10 - $1) = $1.10 - $1 - $0.10 = $0. The ball costs $0.