ANSWER FOR BRAINLIEST AND PLEEASEE EXPLAIN :)

Answer:
8
Step-by-step explanation:
the right angle is 90 degrees, the line is 180 so 180-90 is 90 so 6X+4 + 5X-2= 90 you can counter the -2 by using the +4 so it just becomes +2 90-2=88 so the answer is 8