Question 657298
The answer would be {{{ 65x + 60x = 500 }}}
The way I explain it is, you can think of one 
of the trucks as standing still and the other
one approaching at the sum of their speeds
That gives you {{{ ( 65 + 60 )*x = 500 }}}
for the moving truck. Now convert it to
{{{ 65x + 60x = 500 }}}