A = l x w
= 10 x 20
= 200
this is the area of the first rectangle. now that you know the area, you can subtract it from 500 to then solve the length of the other rectangle.
A = l x w
500-200 = l x 10
300 = l x 10
300/10 = l
30 = l
therefore the length of the second rectangle is 30 feet.
hope this helps! Let me know if you did not understand a step or concept!
