MATH HELP 10 POINTS FOR BEST ANSWER!

I'm sightly confused on how to get the answer, so if you could can you explain to me how to find it?

The question is :In triangle ABC, if line segment , AB is congruent to line segment AC and the measure of angle A is 70 degrees, find the measure of B.

Thank You!

Since AB = AC, angle B = angle C

Angle A = 70

The sum of all 3 angles A + B + C = 180

Since B = C:

A + B + B = 180
70 + 2B = 180
2B = 110
B = 55

So angle B = 55 and angle C = 55:

55 + 55 + 70 = 180

Best of luck!