1) Gathering the data
Pristine charges C1= $19.85 + 32r
Sparkle chargesC2= $61.85 +18r
2) The cost of both are going to be the same when a certain number of rooms is found
C1= C2
19.85 + 32r=61.85 +18r
32r-18r=61.85-19.85
14r=42
r=3
3) So the equation for which the total cost of both house cleaners is the same is:
14r -42=0
Because for r= 3
C1= $19.85 + 32r For 3 rooms
C1= $19.85 + 32(3) =$115.85
C2 =$61.85 +18r For 3 rooms
C2=$61.85 +18(3) =$115.85
