Angle L and Angle M are congruent base angles. Angle N is half of the apex angle. (Look closely and you can see the arrows). 2(6x + 1) + 2(4x - 11) = 180 Distribute the 2's 12x + 2 + 8x - 22 = 180 Combine like terms 20x - 20 = 180 Add 20 to both sides 20x = 200 Divide both sides by 20 x = 10 Plug 10 into the base angle expression. 4x - 11; 4(10) - 11 = 40 - 11 = 29 Angle NLM = 29 degrees