This is an isosceles triangle. It has 2 congruent sides and congruent angles. First, It is a given that an angle measure 42. Since that is the vertex angle, it not equal to the other angles. Using the converse of base angles isosceles triangle, we now the two angles at the bottom are congruent since the lines are equal so both of the bottom angles measure (5x+14). Next, Using Triangle Interior Theorem, a triangle 3 degrees adds up to 180 degrees so we set it equal to that.
