Respuesta :

Simple....

you have:

-12+5k=15-4k

isolate the variable...

-12+5k=15-4k
+12     +12

5k=27-4k

5k=27-4k
+4k   +4k

9k=27

k=3

Thus, your answer.
faizu
-12+5k=15-4k
=> -12 - 15 = -4k - 5k 
=> -27 = -9k
=> -9k = -27 
=> k = -27/-9
=> k = 3

Hope it helps !!!