Explanation:
the first persons mistake:
-6/-3 isn't -2 it's 2 so they divided wrong
the second persons mistake:
they added 7 instead of taking it away which is why they got 8 instead of -6
how to work it out:
-3w+7=1
first take away 7 from both sides
-3w=-6
then divide each side by -3 to get w by itself
w=2