In this case we can use proportions to solve this question.
We know that 4' is to 14' as the height of the barn is to 77'.
[tex]\frac{4}{14}=\frac{x}{77}[/tex]Solve the given proportion:
[tex]\begin{gathered} x=\frac{4}{14}\cdot77 \\ x=22 \end{gathered}[/tex]It means that the barn is 22' tall.