Answer:
k = 10
Explanation:
The external angle of a triangle is equal to the sum of the 2 opposite interior angles.
115° is an exterior angle of the triangle, thus
4k + 5 + 6k + 10 = 115, that is
10k + 15 = 115 ( subtract 15 from both sides )
10k = 100 ( divide both sides by 10 )
k = 10