Well, you're given the values you need to create an equation. So let's take it step by step. He spent $25.75 on popcorn. Then he paid 12.25 for each movie ticket. We don't know how many movie tickets he bought, so we'll put x as the number of tickets for now. In total he spent, 87 dollars.
So the equation should look like 25.75 + 12.25x = 87.00
Once you have the equation, you now have to solve for x. So let's get x by itself!
Subtract both sides by 25.75. So you'll have 12.25x = 61.25.
Divide both sides by 12.25, and you should get x=5, which means Rico bought 5 movie tickets.