Jane is going to fence in her back yard. she has purchased 100 feet of fence she wants to fence in a rectangular area where one side will be the back of her house. she knows her house is 30 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.30x=100 b. x+30=100 c. x+x+30=100 d.30(x+30)=100