Question 167420
17=5+x 
The proper procedure to solve these problems is:
Isolate the unknown item on one side of the equation and all integers on the other side by adding, subtractying, multiplying or dividing.
Thus here we have a +5 on the left side with the x term.
Now subtract 5 from both sides
17-5=5-5+x
12=x is the answer.
Prove by replacing x with 12 and verifying that the equation is valid.
17=5+12
17=17