One angle of a triangle measures 120 degreese. the other two angles are congruent. write and solve an equation to find the measure of the congruent angles.

The total degrees in a triangle is 180.

since the other two angles are the same we can give them the same variable "a"
So a + a + 120 = 180
    
   combine like terms
2a + 120 =180

Subtract 120 from both
2a + 120 -120 = 180 -120
2a = 60

now divide by 2
2a   = 60
2         2      a = 30⁰  

Check 30⁰ + 30⁰ + 120⁰ = 180⁰
                         180⁰       =  180⁰