Question

If isosceles triangle ABC has a 130° angle at vertex B, which statement must be true?
(attached file)

Answer 1

the some of an Isosceles triangle is 180.

if vertex B = 130 degrees then the other two must be equal 50 degrees.  so you divided 50 by 2 which equals 25.

in this case you have 2 points which equal 50. so you take the one which is the closest to 25. which is the last point. m<A = 20 and m<C + 30.
I hope this is right.