It’s easier to take this question step-by-step.
Mark starts with 0 points.
Since he loses 100 points on his first turn, we can subtract.
0 - 100 = -100
From there, he loses another 55 points, meaning we subtract that from his first-turn total.
-100 - 55 = -155
On his third turn, he loses another 65 points, so we subtract from his second-turn total.
-155 - 65 = -220
Therefore, Mark’s total points at the end of three turns is -220.
Hopefully this helps! :)