Ah, great question. Let me help you on this one.
We need to balance both equations for this to work out. This is needed because question asks us for an x variable that will make both equations equal to each other.
Let's write it out so it's easier for us to understand.
Let's not forget to multiply both sides by 100.
[tex]4500+(250x)=375x[/tex]
Let's start by subtracting 45 from both sides.
[tex]4500+(250x)-4500=375x-4500[/tex]
Let's simplify it.
[tex]250x=375x-4500[/tex]
Now, we need to subtract 375 from both sides.
[tex]250x - 375=375x-4500+(-375)[/tex]
Simplify it once again.
[tex]-125x=-4500[/tex]
Divide both sides by -125
[tex]x=36[/tex]
This plan will be the same cost after 36 movies.