What is 17-3n=2

17 - 3n = 2

Move the 17 across to put the n's as the subject

-3n = 2 - 17

-3n = -15

Multiply both sides by -1 so we can work with positives not negatives

3n = 15

Now divide both sides by 3 to make the subject just "n"

n = 5