A: D. m1 + m2 = m3
the exterior angle of a triangle is equal to the sum of the other 2 interior angles
B: 36 deg
plug in the equations given to find m1:
(5x + 11) + (3x+22) = (9x+28), solve for x to get x=5
plug x=5 into the equation for m1 to get 5*5 +11 = 36degrees
you might want to check my work just to be safe
