Answer:
b = 35
Step-by-step explanation:
the sum of the 3 angles in a triangle = 180°
sum the 3 angles and equate to 180
2b - 13 + 2b - 11 + 2b - 6 = 180 , that is
6b - 30 = 180 ( add 30 to both sides )
6b = 210 ( divide both sides by 6 )
