Question

 how do i solve this problem 4s -12 = -5s + 51 

Answer 1

4s-12=-5s+51
  +12=     +12
4s=-5s+63
+5s =+5s
9s=63
9/9=63/9
s=7

Answer 2

$4s-12=-5s+51\ \ \ \ /+12\\\\4s-12+12=-5s+51+12\\\\4s=-5s+63\ \ \ /+5s\\\\4s+5s=-5s+5s+63\\\\9s=63\ \ \ /:9\\\\9s:9=63:9\\\\s=7$