The answer of this question is going to be 90
The walls are vertical so the angle opposite X would be a right angle which is 90 degrees.
X would be 180 - 90 - 35 = 55 degrees
X and 2y - 5 are complementary angles which add together to equal 90:
2y - 5 + 55 = 90
Simplify:
2y +50 = 90
Subtract 50 from both sides:
2y = 40
Divide both sides by 2:
y = 20
(17*3) --- to find the total points of the 3 quizzes
17*3=51
the third quiz grade=51-14-19=18
hope this helps