Answer:
m∠R = 69
Step-by-step explanation:
m∠R + m∠S + m∠T = 180 {Angle sum property of triangle}
5x - 11 + 3x - 3 + 3x + 18 = 180
5x + 3x + 3x - 11 - 3 + 18 = 180 {Combine like terms}
11x +4 = 180
11x = 180 - 4
11x = 176
x = 176/11
x = 16
m∠R = 5x - 11
= 5*16 - 11
= 80 - 11
m∠R = 69
