Answer:
[tex]m\angle RST=41^o[/tex]
Step-by-step explanation:
The picture of the question in the attached figure
we know that
The measure of the external angle is the semi-difference of the arcs it covers.
so
[tex]m\angle RST=\frac{1}{2}[arc\ RT-arc\ UV][/tex]
substitute the given values
[tex]m\angle RST=\frac{1}{2}[107^o-25^o][/tex]
[tex]m\angle RST=\frac{1}{2}[82^o][/tex]
[tex]m\angle RST=41^o[/tex]
