Be careful when you only know one of the three angles. In this triangle, two missing angles are both labeled "x." Since they're labeled with the same variable, you know they are congruent.
Set up an equation with what you know:
36 + x + x = 180
Then, solve for the variable.
36 + x + x = 180
36 + 2x = 180
36 − 36 + 2x = 180−36
2x = 144
x = 72
Each of the two missing angles measures 72 degrees.