Answer:
x = 5
Step-by-step explanation:
The sum of two interior angles in a triangle is equal to an exterior angle that's supplementary to the third interior angle
Therefore m<A + m<B = m<C
13x - 11 + 4x + 1 = 18x - 15 add like terms
17x - 10 = 18x - 15
15 - 10 = 18x - 17x
5 = x
