Jane is going to fence in her back yard. She has purchased 150 feet of
fencing and knows that she wants to fence in a rectangular area where one
side will be the back of her house. She knows her house is 40 feet across the
back. Which of the following is the equation that Jane can use to figure out
how far back from the house she can fence in?

A. 40(x + 40) = 150
B. 40x = 150
c. x+x+ 40 = 150
D. x+ 40 = 150