Answer
$(a)\space15.64\space m/s$
$(b)\space51.3\space ft/s$
Work Step by Step
(a) We know 1 mi = 1609 m and 1 h = 3600s
First of all, let's convert 35 mi/h into m/h as follows.
$35\space mi/h\space = (\frac{35\space mi}{h})\times(\frac{h}{3600\space s})$
$\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space=\space 56315\space m/h$
After that let's convert h into s as follows.
$35\space mi/h\space =\space 56315\space m/h$
$\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space =\space (\frac{56315\space m}{h})\times(\frac{h}{3600\space s})$
$\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space =\space 15.64\space m/s$
(b) we know 1 m = 3.28 ft
Now we can multiply the result in (a) by 3.28 ft/m to get the answer
$35\space mi/h\space =\space 15.64\space m/s\space =\space 15.64\space m/s\space \times\space 3.28\space ft/m$
$\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space =\space 51.3\space ft/s$
