Answer:
20
Step-by-step explanation:
Altitudes create 90 degree angles, so if one side is (4x + 10)°, the other must be as well.
Now, set (4x + 10)° equal to 90° to solve for x.
Solve like so:
4x + 10 = 90
-10 from each side
4x = 80
/4 from each side
x = 20
If you want to check:
4x + 10 = 90
4(20) + 10 = 90
80 + 10 = 90
90 = 90
