In triangle $A B C,$ line $t$ is drawn through vertex $A$ in such a way that $t \| \overline{B C}$
a) Which pairs of $\angle \mathrm{s}$ are $\cong ?$
b) What is the sum of $m \angle 1$ $\mathrm{m} \angle 4,$ and $\mathrm{m} \angle 5 ?$
c) What is the sum of measures of the $\angle \mathrm{s}$ of $\triangle A B C ?$
(FIGURE CAN'T COPY)