AMC 8 1988 Problem 5

If $\angle \text{CBD}$ is a right angle, then this protractor indicates that the measure of $\angle \text{ABC}$ is approximately

$\text{(A)}\ 20^\circ \text{(B)}\ 40^\circ \text{(C)}\ 50^\circ \text{(D)}\ 70^\circ \text{(E)}\ 120^\circ$