Answer:
80°
Explanation:
<A+<B+<C=180
30+<B+70=180
100+<B=180
<B=180-100
= 80
consider triangle ABC and triangle EDC
AC=CE (given
BC=CD (given
<ACB=<ECD (vertically opposite angles are equal)
therefore triangle ABC is congruent to triangle EDC
<B=<D (CPCT)