Question 1075822
<pre>
Make unit multipliers:

{{{matrix(1,10,20,m/s,""="",matrix(1,2,20,m/s),"×",matrix(1,2,1,km)/matrix(1,2,1000,m),"×",matrix(1,2,60,s)/matrix(1,2,1,min),"×",matrix(1,2,60,min)/matrix(1,2,1,hr))}}}

Cancel the meters

{{{matrix(1,10,20,m/s,""="",matrix(1,2,20,cross(m)/s),"×",matrix(1,2,1,km)/matrix(1,2,1000,cross(m)),"×",matrix(1,2,60,s)/matrix(1,2,1,min),"×",matrix(1,2,60,min)/matrix(1,2,1,hr))}}}

Cancel the seconds

{{{matrix(1,10,20,m/s,""="",matrix(1,2,20,cross(m)/cross(s)),"×",matrix(1,2,1,km)/matrix(1,2,1000,cross(m)),"×",matrix(1,2,60,cross(s))/matrix(1,2,1,min),"×",matrix(1,2,60,min)/matrix(1,2,1,hr))}}}

Cancel the minutes

{{{matrix(1,10,20,m/s,""="",matrix(1,2,20,cross(m)/cross(s)),"×",matrix(1,2,1,km)/matrix(1,2,1000,cross(m)),"×",matrix(1,2,60,cross(s))/matrix(1,2,1,cross(min)),"×",matrix(1,2,60,cross(min))/matrix(1,2,1,hr))}}}

And all we have left is

{{{matrix(1,10,20,m/s,""="",20,"×",(km)/1000,"×",60,"×",60/h)}}}{{{""=""}}}{{{matrix(1,2,("20×60×60")/1000,km/h)}}}

or

{{{matrix(1,5,20,m/s,""="",72,km/h)}}}

No, he won't get a speeding ticket.

Edwin</pre>