12 + 5k + 15 -24
------------------- = -----------------------
k + 3 k - 4
5k + 27 -24
------------ = ---------------
k + 3 k - 4
(k - 4)(5k + 27) = -24 (k + 3)
5k^2 - 20k + 27k -108 = - 24k - 72
5k^2 + 31k - 36 = 0
(5k + 36)(k - 1) = 0
5k + 36 = 0; k = -36/5 = -7.2
k - 1 = 0; k = 1
solutions
k = 1 and k = -7.2