Triangle B C D. The exterior angle at B is labeled 1 and the interior angle is labeled 2. Angle C has measure 70 degrees. The exterior angle at D has measure 130 degrees.
A. m∠BCD − m∠DBC = 10°
B. m∠BCD − m∠DBC = 20°
C. m∠BCD − m∠DBC = 60°
D. m∠BCD − m∠DBC = 80°
