Answer:
m<ADC= 180-m<ABC or m<ABC=180-m<ADC
Explanation:
Firstly, we need to establish that trapezoid ABCD is an isosceles trapezoid. By doing so, we know that angles opposite one another in an isoseles trapezoid are supplementary. As a result, m<ACD+m<ABC= 180. We can now solve for angle ACD or ABC.