Story problem equation

Question

At discovery preschool, parents who have two children enrolled get a discount on the second child's enrollment fee. The second child's enrollment fee is $10 less per day than the first child's. If Tess has two children enrolled for 5 days and her total bill is $200, how much does she pay for the first child to attend daycare? The answer is 25 but what's the equation?

Answer 1

Let x be the first child’s enrolment fee per day, which is 5x for 5 days, then the second child’s is 5x-50 for 5 days.

Total fee is 5x+5x-50=200.

10x=250, x=$25.