For Question #3, We can use the properites of equality to isolate t
-9 + t = 12
+9 +9
t= 21 , and this is correct because when you plug 21 back into t 12 =12.
For Question #4, We can also use the properties of equality to isolate w
3w=96
/3 /3
w = 32, and when you check it my substituting 32 you get 96=96