we can use Cross-multiplication
[tex]\begin{gathered} \frac{4}{5}\longrightarrow\frac{1}{2} \\ 1\longrightarrow x \end{gathered}[/tex]the left column is the hour and right tank level
we can find x
[tex]x=\frac{1\times\frac{1}{2}}{\frac{4}{5}}[/tex][tex]\begin{gathered} x=\frac{\frac{1}{2}}{\frac{4}{5}} \\ x=\frac{5}{8} \end{gathered}[/tex]so in one hour she fills 5/8 of the tank
