Hi guys, I'm struggling to set up this problem into numbers

I'm thinking x=number of benches and y=different number of benches, soIf a teacher can place her students four to a bench, there will be three students on the final bench. But, if five children are placed on each bench, there will be four students on the last bench.

What is the smallest number of the children the class could have?

4x+3=5y+4

Not really sure where to go from there? Any light shed would be greatly appreciated!