How can symbols and absolute value you to order sets of integers

How is working backward similar to solving an equation?

Maren is buying carpet for her rectangular living room. the room is 4.8 yards wide and 5.2 yards long. how much carpet does she need to buy? enter your answer as a decimal in the box. yd2

X^2/100+y^2/25=1 the length of the major axis is: a)5 b)10 c)20