Answer:
m/angle ABC=47^o
Explanation:
we know that
The measure of the external angle is the semi-difference of the arches it covers
so
m\angle ABC=\frac{1}{2}[arc\ DE-arc\ AC]
substitute the given values
m\angle ABC=\frac{1}{2}[142^o-48^o]
m\angle ABC=47^o