Question

26 = w - 12 show me how you got this answer

Answer 1

26=w-12
+12  +12
38=w
That is your answer

Answer 2

Undo what has been done. First try to isolate the variable. So 12 is being subtracted by the variable. So you add 12 to each side. 
 26+12=w-12+12
Undo what has been done means to do the opposite of what is done. So now you are left with 38=w. If you added 12 to each side.