Answer:
58
Step-by-step explanation:
The measure of the outer angle is equal to the angles opposite of it. So, 138 = 10x-2+13x+2.
Simplify this into 138 = 23x
Divide to get x = 6.
Take the equation from angle A and substitute x for 6.
10*6= 60. 60-2 = 58.
