Solve for a in the diagram below.

20

Step-by-step explanation:

We can tell from the little square in the corner that this is a 90 degree angle, so all three of the expressions of x should add up to 90:

x + 2x + (x + 10) = 90

Combine like terms:

4x + 10 = 90

4x = 80

Divide by 4:

x = 80/4 = 20

The answer is 20.

Hope this helps!

20

Step-by-step explanation:

Angles form a right angle, hence they add up to 90

x + 2x + x + 10 = 90

4x + 10 = 90

4x = 80

x = 20