What is m∠cad? a. 20º b. 80º c. 100º d. 110º

m∠CAD = 80 + 20 
m∠CAD = 100

answer
m∠CAD = 100
C. 100º

Theorem:
The measure of an exterior angle of a triangle is equal to the sum of the measures of the remote interior angles.

<CAD is an exterior angle of triangle ABC.
Interior <CAB is adjacent to exterior <CDA.
Remote means far away.
The remote interior angles of <CAD are angles B and C.

m<CAD = m<B + m<C

m<CAD = 20 + 80

m<CAD = 100 deg

There should only be 1 solution