AMC 10 2008b Problem 24

Quadrilateral $ABCD$ has $AB = BC = CD$, $m\angle ABC = 70^\circ$ and $m\angle BCD = 170^\circ$. What is the degree measure of $\angle BAD$? $\mathrm{(A)}\ 75 \mathrm{(B)}\ 80 \mathrm{(C)}\ 85 \mathrm{(D)}\ 90 \mathrm{(E)}\ 95$