Answer: x = 20.
Step-by-step explanation:
x and (3x + 10) combine to form a right angle, shown in the diagram by the small square joining the perpendicular lines.
Right angles are 90 degrees, so you can add both angles to get 90:

If there was a chart with this that would be helpful but at this time with the information you have given you can not solve this problem
The answer is B because 2/5 is greater than 5/12
B. complementary because 126+54= 180°