# 4.3.8 Overall Cost

## Activity: The Price of Doing it Yourself

Now that I’ve determined how many rolls of insulation I need to buy, what will the total cost be of doing the job myself?

Remember:

• Each roll costs $9. • There is a “three-for-two” sale. • I will also need to buy some safety equipment. ### Answer Since I purchased 20 rolls of insulation, I will be able to take advantage of the “three-for-two” sale. This means that for every three rolls I purchase, I only pay for two rolls. Recall that each roll costs$9. Thus, for every set of three rolls I purchase, I will be charged only .

To determine how many times I will get to take advantage of the sale, we can use a picture.

Since there are six sets of three rolls, it will cost . Unfortunately, the two additional rolls won’t be on sale, so the insulation will cost .

Don’t forget that the safety gear is \$45. This puts the charges at .

4.3.7 Determining the Number of Rolls

4.3.9 Decision Time