one angle of a triangle measures 120 the other two angles are congruent. what is the measure of the two congruent angles

Question

i have to write and solve an equation 

Answer 1

In general, if the measures of three angles of a triangle are a, b and c, you know that a+b+c=180 degrees.

But suppose c = 120, and a and b are equal; then you write a + a + 120 = 180.

Understand? Solve for a.