Answer
\begin{array}{c|ll}& \textbf{Statement} & \textbf{Reasons}
\\\hline1 & \text{m}\angle{GFI} \text{ = 128} & \text{Given}
\\2 & \text{m}\angle{GFE}\text{ + m}\angle{EFI}\text{ = m}\angle{GFI} & \text{Angle Addition Postulate}
\\3 & \text{9x - 2 + 4x = 128} & \text{Substitution Property}
\\4 & \text{13x - 2 = 128} & \text{Distributive Property}
\\5 & \text{13x = 130} & \text{Addition Property of Equality}
\\6 & \text{x = 10} & \text{Division Property of Equality}
\\7 & \text{m}\angle{EFI}\text{ = 4x} & \text{Given}
\\8 & \text{m}\angle{EFI}\text{ = 4(10)} & \text{Substitution Property}
\\9 & \text{m}\angle{EFI}\text{ = 40} & \text{Simplify}
\end{array}
Work Step by Step
Substitute the measures shown in the diagram and solve for x.
Use the value you found for x to find $m\angle {EFI}$.
