June :
900 + 0.02(48,500) + 0.018(48500 - 17500) =
900 + 970 + 558 = 2428 <==
July :
900 + .02(50,200) + 0.018(50200 - 17500) =
900 + 1004 + 588.60 = 2492.60 <===
Replace X and Y in the given equations and see if they are true:
2(5) + 2(1) = 10+2 = 12... does not equal 11 So this in not right.
2(5) +3(1) = 10 + 3 = 13 this is correct.
The answer would be: 2x+3y=13