Jane is going to fence in her back yard. she has bought 100 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 if 30 ft 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) 30(x+30) = 100
b) 30x = 100
c) x+x+30 = 100
d) x+30 = 100