Answer: ∠BAC = 70°
Explanation:
We will use the "Exterior Angle Property" which states that an exterior angle of a triangle is equal to the sum of its two opposite non-adjacent interior angles.
This means that (6a) + (7a) = 130° which we can solve.
(6a) + (7a) = 130°
13a = 130
a = 10°
Now that we have the value of a, we can solve for the angle BAC.
7a
7(10)
70°