Answer
m$\angle$A=52$^{\circ}$
m$\angle$B=64$^{\circ}$
m$\angle$C=64$^{\circ}$
Work Step by Step
m$\angle$B=m$\angle$C=m$\angle$A+12
m$\angle$A+m$\angle$B+m$\angle$C=180
m$\angle$A=m$\angle$A+12+m$\angle$A+12=180
3m$\angle$A=156
m$\angle$A=52^{\circ}$
m$\angle$B=m$\angle$C=52+12=64$^{\circ}$