Mabel sold her undivided one-third interest in an apartment building, in which she ahd a $40,000 adjusted basis, for $110,000. The buyer paid $15,000 down, assumed Mabel's share of the mortgage, and signed an installment obligation with a face value of $50,000. $5,000 of principal was paid at the end of the year of sale. what are Mabel's contract price, gross profit percentage, and payment in the year of sale ?