Given that the average speed from home to office to home is 60 mph.
Speed from home to office,
[tex]S_1=30\text{ mph}[/tex]Let the formula for average speed is
[tex]\begin{gathered} \text{Average sp}eed=\frac{S_1\times S_2}{2}_{} \\ 60=\frac{30\times S_2}{2} \\ 30\times S_2=60\times2 \\ 30\times S_2=120 \\ S_2=\frac{120}{30} \\ S_2=40 \end{gathered}[/tex]Hence the speed he took from office to home is 40 mph.
