If △abc is an isosceles triangle where ab¯≅ac¯, m∠a=(2x−20)°, and m∠b=(3x+5)°, then m∠c=°.

 Let ABC be an isosceles triangle with AB = AC.  Let M denote the midpoint of BC (i.e., M is the point on BC for which MB = MC).  Thena)      Triangle ABM is congruent to triangle ACM.b)      Angle ABC = Angle ACB (base angles are equal)c)      Angle AMB = Angle AMC = right angle.d)      Angle BAM = angle CAM