Answer:
m<R = 65
Step-by-step explanation:
m<R + m<S + m<T = 180° (sum of interior angles in a triangle)
(5x - 11) + (3x - 3) + (3x + 18) = 180°
Solve for x.
5x - 11 + 3x - 3 + 3x + 18 = 180
Add like terms
11x + 4 = 180
11x = 180 - 4
11x = 176
x = 16
m<R = (5x - 11)
Plug in the value of x
m<R = 5(13) - 11
m<R = 65
