What are the steps on how to factor the difference of squares?

Reflect the point (7,0) across the y-axis

What is the perimeter of a rectangular building that is 80 feet wide and 140 feet deep?

Money off coupons have been circulated to 300 households. only 2/5 of these were redeemed (used) in the local supermarket to get a free shampoo. what fraction of coupons were unused? (ps: write how you got the answer)