x + y = 3k x - y = k Add the equations term by term just as they are and the terms in y will cancel: x + y = 3k x - y = k ----------- 2x = 4k Divide both sides by 2 x = 2k Multiply the second equation x - y = k through by -1 making it -x + y = -k Then add it to the first equation term by term and the terms in x will cancel: x + y = 3k -x + y = -k ----------- 2y = 2k Divide both sides by 2 y = k Answer (x,y) = (2k,k) Edwin