Question 21318
oct=12 more than sept


sept=x
oct=x+12
nov=twice as much as sept 
nov=2x


to find how much they used each month, add them up and equate it to 132
x+x+12+2x=132
4x+12=132
4x=120
x=30


sept=x=30
oct=x+12= 30+12=42
nov=2x=2(30)=60


check:
30+42+60=132