Acar accelerates uniformly from rest to a speed of 76.8 mi/h in 7.62 s. find the constant acceleration of the car. answer in units of m/s2

Acceleration = (change in speed) / (time for the change)

                   =      (76.8 mi/hr)    /       (7.62 sec)

                   =        10.08  mile/hour-second

That quantity is a perfectly good acceleration, it has the right
dimensions etc, but the question asks for it in units of meter/s²,
so I have to convert it to the equivalent in meter/s².

         (10.8  mile / hr-sec) x (1,609 meter/mile) x (1 hr / 3600 sec)

      =   (10.8 · 1,609 · 1) / (3,600)       meter / second²

      =        4.83 meter / second²   if you round all the numbers as you go
or 
                4.51 meter/sec²     if you use a calculator and don't round anything