Egbert M. answered 06/22/20
Precalculus is the most important "next step" in Math after Algebra!
The equations are 8x + 2y = 22 and 4x + 5y = 5. Multiplying the second equation by 2 and subtracting the first from it gives 8y = -12$, so there must be a typo in the question. If the second day sale was $15, then 8y=8$ ($1 per child) and 8x=20, or $2.50 per senior.