Question 708665
The sum of their distances traveled in the time to meet is the distance between towns A and B.  Time is h, for time in HOURS.


Truck: {{{(d/30)*h}}}, the distance moved in h hours
Car: {{{(d/20)*h}}}

{{{(d/30)*h+(d/20)*h=d}}}
Divide both sides by d,
{{{(1/30)*h+(1/20)*h=1}}}
Combine terms of h,
{{{(1/30+1/20)h=1}}}
{{{((2+3)/60)h=1}}}
{{{(5/60)h=1}}}
{{{(1/12)h=1}}}
{{{highlight(h=12)}}},  12 hours.