y = base pay + (variable pay x)
37.50 = base pay + (variable pay 5)
75 = base pay + (variable pay 20)
let v be the variable pay:
base pay = y - variable pay x
37.50 - 5v = 75 - 20v
-5v + 20v = 75 - 37.50
15v = 37.50
v = 37.50/15
v = 2.5
37.50 - 5(2.5) = 75 - 20(2.5)
37.50 - 12.50 = 75 - 50
25 = 25
base pay is 25 ; variable pay is 2.50 per newspaper delivered.
y = 25 + 2.50x