A contractor charges $1,200 for 100 square of roofing installed. At this rate,
how much does it cost to have 1,100 square feet installed?

The contractor charges $13,200

For 1,100 square feets

Step-by-step explanation:

To solve the problem we need to understand how to charges

Step one

Given

For each 100 square feet of roofing he charges $1,200

Hence for 1,100 square feet we can see that the charges is 11times

This is because 1100/100= 11

Step two :

Hence he charges 11 times more

Therefore his fee for 1,100 square feet is

1200*11=$13,200