The bottom triangle is equal to the top triangle because the marks on the side of the triangle show congruence (from the word congruent, meaning equal).
so if they are equal they have the same angle measurement.
hint: in the top triangle, the angle measurement next to the 2 marks (32) has the same value as the angle next to the angle next to the 2 marks on the bottom triangle.
Once you have found the two angle measurements, add them up and subtract them from 180 (because every triangle equals 180 degrees) to get the angle measurement for angle b.