Question 211588
First thing, let's get rid of the 2 rest hours. That says the the man is actually moving for 3 hours.

You also know he goes as far at 30mph as he returns at 20mph. 
Let the distance he goes each way be represented by d
Let the time at 30mph be given by t. Then the time at 20mph is {{{3-t}}}
{{{d = 30 * t}}}
{{{d = 20 *(3-t)}}}
so {{{30t = 20*(3-t)}}}
{{{30t = 60 - 20t}}}
{{{50t = 60}}}
{{{t = 6/5}}}
So the man travels at 30mph for 6/5 hour
{{{d = 30*(6/5)}}} = {{{36}}} miles
Check your answer.
Does {{{36 = 20(3-(6/5))}}}