N = 82
The angle at the bottom right is a supplementary angle, and its also a vertical angle with O. If it’s 140, the angle inside the triangle would be 180-140. So that angle is 40. Then the angle on the bottom left is a vertical angle. Vertical angles always have the same number, so if it’s 58, the angle inside the triangle is also 58. So that’s 2 angles. Add them up, they equal 98. All the angles in a triangle should add up to 180, so if those two add up to 98, do 180-98=82. So our third angle, N, would be 82. Hope this helps!