Answer
There are 2 errors in the solution; I would grant the student 8/10
Work Step by Step
The original exercise is:$$-3(x - 6) = 2-x$$ When the student used the distributive property, he did the following: $$-3x - 18 = 2-x$$ His first mistake lies in making the $18$ a negative number, since multiplying -3 by -6 gives positive $18$, as follows: $$-3x + 19 = 2-x$$ His second mistake was when he subtracted -18 on both sides, yielding -16. If he'd done it correctly, he would've reached the following expression:$$-2x - 18 = 2$$ $$-2x = 2 - (-18)$$ $$-2x = 2 + 18$$ $$-2x = 20$$.
Since he made 2 mistakes and the importance of doing these exercises is not the answer itself, but the process of how to get to the answer.
