Answer:
60
Step-by-step explanation:
horizontal plane = 180
therefore 180 - b + 27 = 180
this will give us the missing inner angle
then we create a linear equation to get the value of b, and since the sum of the inner angles of the triangle = 180
b - 7 + b - 26 + (180 - 27 - b) = 180
b = 60
