Answer:
x=12
Step-by-step explanation:
The two angles shown are complementary angles, so the add to 90 degrees
x+42 + 3x = 90
Combine like terms
4x+42 = 90
Subtract 42 from each side
4x+42-42 = 90-42
4x = 48
Divide by 4
4x/4 = 48/4
x = 12
