Solve and check the answers in the original equation

 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

Where are the following equations?

None because i don’t know.