Question 1162013
The fuel efficiency of a certain car is 31.0 miles per gallon. Convert the efficiency into kilometers per litre. 

The conversion factor from gallons to litres is: 1 gal = 3.79 L.
<pre>1 gallon = 3.79 L             1.609344 kilometers = 1 mile
Using DIMENSIONAL ANALYSIS, we get: {{{matrix(1,5,
matrix(1,2, 31, mile(s))/matrix(1,2, 1, gallon(s)), "x", matrix(1,2, 1, gallon(s))/matrix(1,2, 3.79, liter(s)), "x", matrix(1,2, 1.609344, kilometer(s))/matrix(1,2, 1, mile(s)))}}}
{{{matrix(1,5, matrix(1,2, 31, cross(mile(s)))/matrix(1,2, 1, cross(gallon(s))), "x", matrix(1,2, 1, cross(gallon(s)))/matrix(1,2, 3.79, liter(s)), "x", matrix(1,2, 1.609344, kilometer(s))/matrix(1,2, 1, cross(mile(s))))}}} ------ Canceling ALL appropriate measurements
{{{highlight_green(matrix(1,7, 31(1.609344)/3.79, kilometer(s)/liter(s), "=", 13.16349974, kilometers, per, liter))}}}