ANSWER
[tex]0.8\text{ lawns per hour}[/tex]EXPLANATION
To find Tanisha's rate of mowing the lawn per hour, divide the number of lawns mown by the total time (in hours) taken to mow them.
That is:
[tex]\begin{gathered} \frac{8}{10} \\ \Rightarrow0.8\text{ lawns per hour} \end{gathered}[/tex]That is the answer.