Answer:
x = 15
Explanation:
The exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.
∠ KLM is an external angle of the triangle, thus
∠ KLM = ∠ JKL + ∠ KJL , substitute values
5x - 7 = x + 20 + 2x + 3
5x - 7 = 3x + 23 ( subtract 3x from both sides )
2x - 7 = 23 ( add 7 to both sides )
2x = 30 ( divide both sides by 2 )
x = 15