Answer
$2807 mph$
Work Step by Step
$1m=6.21371\times10^{-4}mile$
$1255m=1255\times(6.21371\times10^{-4}mile)$
$1s=\frac{1}{3600} h$
$\frac{1255\times(6.21371\times10^{-4}mile)}{\frac{1}{3600}}$
$=255\times(6.21371\times10^{-4}mile)\times 3600$
$=2807.354178 \ mph$
$=2807 \ mph$