Abat and a ball cost one dollar and ten cents in total. the bat costs a dollar more than the ball. how much does the ball cost?

You can solve this with a system of equations.
B = How much the bat costs
S = How much the ball costs

The bat and the ball together cost 1.10, so your first equation will be b + s = 1.10. You also know that the bat costs 1 dollar more than the ball, so your second equation will be s + 1 = b. Now, since the second equation is already solved for b, plug that value into the first equation.

     b + s = 1.10   Plug in the b-value
s + 1 + s = 1.10   Combine like terms (s and s)
   2s + 1 = 1.10    Subtreact 1 from both sides
        2s = .10     Divide both sides by 2
          s = .05

Now, plug the s value into the second equation and solve for b.

 s + 1 = b    Plug in the s-value
.05 + 1 = b   Add
    1.05 = b

Now you know that the bat costs $1.05 and the ball costs $.05

First set up an equation: b+(b+1)=1.10, ball=b, bat=b+1. Combine like terms, the b's: 2b+1=1.10. Subtract 1 from both sides: 2b=.10. Divide both sides by 2: b=.05. The ball =.05¢. Plug into equation: .05+(.05+1)=1.10. Solve: .05+1.05=1.10. 1.10=1.10 ✔️ The ball=.05 and the bat=1.05 :) This is just an easier way to do what Dasetka said, I hope it makes sense :)