Answer
a - Speed in miles per hour =39.6 $\frac{mi}{hour}$.
b - Speed in km per hour = 63.75 $\frac{km}{hour}$.
c - Gas mileage in km per liter =11.4 $\frac{km}{L}$.
Work Step by Step
Speed is calculated: speed = $\frac{distance}{time}$
a - Speed in miles per hour = $\frac{distance (miles)}{time(hours)}$
Speed in miles per hour = $\frac{832(miles)}{21(hours)}$
Speed in miles per hour =39.6 $\frac{mi}{hour}$
b - Speed in km per hour = $\frac{distance (km)}{time(hours)}$
First we convert miles into km, knowing that 1 mi = 1.609 km.
832 mi = 832 mi x $\frac{1.609 km}{1 mi}$
832 mi = 1,338.7 km
Speed in km per hour = $\frac{1,338.7(km)}{21(hours)}$
Speed in km per hour = 63.75 $\frac{km}{hour}$
c - Gas mileage in km per liter = $\frac{distance (km)}{volume(L)}$
First we convert the volume from gal to L knowing that 1 gal = 3.79 L.
31 gal = 31 gal x $\frac{3.79 (L)}{1 (gal)}$
31 gal = 117.4 L
Gas mileage in km per liter = $\frac{distance (km)}{volume(L)}$
Gas mileage in km per liter = $\frac{1,338.7(km)}{117.4(L)}$
Gas mileage in km per liter =11.4 $\frac{km}{L}$
