Answer
$20.11\space m/s $
Work Step by Step
According to appendix C, 1 mi = 1609 m, so we can multiply miles by the ratio 1609 m/mi to get meters. As well as 1 h = 3600 s, So we can use the conversion factor 3600 s/h to convert hours to seconds. Combining these two conversions gives,
$45 mi/h = (\frac{45\space mi}{h})\times(\frac{1609\space m}{mi})\times(\frac{1\space h}{3600\space s})$
$\space\space\space\space\space\space\space\space\space\space\space\space\space= \frac{72405}{3600}\space m/s$
$\space\space\space\space\space\space\space\space\space\space\space\space\space=20.11\space m/s$
$$The\space answer\space \space is\space 20.11 m/s$$
