The square shown at the bottom left corner indicates that it is 90 degrees.
To find the value of x you must set the equation up to equal 90 degrees.
x + 2x + (x + 10) = 90
3x + x + 10 = 90
4x + 10 = 90
Subtract 10 from both sides.
4x = 80
Divide both sides by 4.
x = 20
Answer: x = 20
