Chris had 3/5 as many rocks as Melody. Melody gave 7 rocks to Chirs so that they would each have the same amount. How many rocks did the two have altogether?

Let Melody's rocks = M

Let Chris's rocks = (3/5)M

So

M - 7 = (3/5)M + 7 simplify

M - (3/5)M = 7 + 7

(2/5)M = 14 multiply both sides by 5/2

M = 14 (5/2) = 35

(3/5)M = (3/5) (35) = 21

35 + 21 = 56 all together