Question 1031174
<pre><b>
{{{matrix(1,14,800,km/h,""="",matrix(1,2,800,km/h),"×",matrix(1,2,1000,m)/matrix(1,2,1,km),"×",matrix(1,2,100,cm)/matrix(1,2,1,m),"×",matrix(1,2,1,in)/matrix(1,2,2.54,cm),"×",matrix(1,2,1,ft)/matrix(1,2,12,in),"×",matrix(1,2,1,mi)/matrix(1,2,5280,ft))}}}

Then cancel all the units that will cancel:

{{{matrix(1,14,800,km/h,""="",matrix(1,2,800,cross(km)/h),"×",matrix(1,2,1000,cross(m))/matrix(1,2,1,cross(km)),"×",matrix(1,2,100,cross(cm))/matrix(1,2,1,cross(m)),"×",matrix(1,2,1,cross(in))/matrix(1,2,2.54,cross(cm)),"×",matrix(1,2,1,cross(ft))/matrix(1,2,12,cross(in)),"×",matrix(1,2,1,mi)/matrix(1,2,5280,cross(ft)))}}}

And we have left:

{{{matrix(1,14,800,km/h,""="",800/h,"×",1000/1,"×",100/1,"×",1/2.54,"×",1/12,"×",matrix(1,2,1,km)/5280)}}} {{{""=""}}}{{{matrix(1,2,497.0969538,mi/h)}}}

Then use {{{TIME=DISTANCE/SPEED}}}{{{""=""}}}{{{matrix(1,2,1822,mi)/matrix(1,2,497.0969538,mi/h)}}}{{{""=""}}}{{{matrix(1,2,3.66528096,hours)}}}{{{""=""}}}{{{matrix(1,8,3,hours,",",39,minutes,",",55,seconds)}}}

Edwin</pre>