Find the value of x.
and please show how you got to the answer

Because a triangle is 180 degrees, and you already have a right angle that leaves 90 degrees for the rest of the angles.
So, (2x) + (x+15) = 90
Combine like terms.
3x + 15 = 90
Subtract 15 from 90.
3x = 75
Divide.
75/3, so x = 25.