Chelsea already spent $20 and $15:
[tex]45-20-15=10[/tex]So now she has $10 left to spend on the game she wants to play. If the number of times she plays this game is x and the game costs $0.65, you can model this with the following inequation:
[tex]0.65\cdot x\leq10[/tex]If we clear the x from here, we can find the maximum number of times that Chelsea can play this game:
[tex]x\leq\frac{10}{0.65}[/tex][tex]x\leq15.3846[/tex]Since the number of times she can play must be a whole number (you can't play 15.3 times) and this number must be under 15.3846, the maximum number of times Chealsea can play this game is 15.
Bonus: if you substract 15 from the previous result and multiply by how much the game costs, you can get how much money Chealsea has left:
[tex](15.3846-15)\cdot0.65\cong0.25[/tex]So she leaves the fair with $0.25 after playing the maximum number of times on the game.