Refer to the figure below, in which $m(\angle 1)+m(\angle 3)+$ $\mathrm{m}(\angle 4)=180^{\circ}, \angle 3 \cong \angle 4,$ and $\angle 4 \cong \angle 5 .$ Find the

measure of each angle.

a. $\angle 1$

b. $\angle 2$

c. $\angle 3$

d. $\angle 6$

(figure not copy)