Answer:
x = 12
Step-by-step explanation:
The 2 angles add up to 90 degrees, so 3x + x + 42 = 90
3x + x + 42 = 90
Subtract 42 from both sides:
3x + x = 48
3x + x = 4x, so
4x = 48
Divide both sides by 4:
