Explanation:
if I understand correctly, then the equally marked angles in both triangles are the same.
so, the angles at B and M are 40°.
and the angles at K and C are 3x - 5.
if that is true, then we need to remember that the sum of all angles in a triangle is always 180°.
and so, we can use the triangle KLM to find x.
180 = 40 + 2x + 3x - 5
140 = 5x - 5
145 = 5x
x = 29