Contrary to the above answer, the ball does not cost $0.10! If the ball were to cost 0.10 then the bat must cost $1.00 which is only $0.90 more than the ball! We can solve this equation correctly using an expression like so:
b = price of the ball
b + 1 = price of the bat
b + (b + 1) = price of the ball + price of the bat
b + b + 1 = 1.10
Therefore reareanging the equation:
2b = 0.10
And therefore:
b = 0.05
So the ball costs $0.05 and the bat costs $1.05 :))