Answer:
D. 20°
Step-by-step explanation:
The entire angle = 90 degrees you can tell that from the corner indicator
Set the two expressions equal to 90
(3x+10) + (x) = 90
Combine like terms
4x + 10 = 90
Subtract 10 from both sides to cancel it out
4x = 80
Divide each side by 4
x = 20
Check it by substituting x for 20
3(20) + 10 = 70 x = 20 70 + 20 = 90
