Answer:
130°
Step-by-step explanation:
[tex]e = \frac{1}{2} (100 \degree - 80 \degree) \\ \\ e = \frac{1}{2} \times 20 \degree \\ \\ e = 10 \degree \\ \\ a = \frac{1}{2} \times 80 \degree \\ \\ a = 40 \degree \\ \\ by \: interior \: \angle \: sum \: postulate \: of \: a \: \triangle \\ a + e + f = 180\degree \\
40\degree + 10\degree + f = 180\degree \\
50\degree + f = 180\degree \\
f = 180\degree - 50\degree \\
\huge \red {\boxed {f = 130\degree}} [/tex]
