<PRE><B>Question 30683</B>
let the speed together be x
Hot tub can fill one portion of the tub is x/25 minutes.
Equation:
{{{x/25+x/20}}}
25*20=500
{{{20x/500+25x/500}}}
{{{45x/500}}}
45x=500
x=11.11


Hence, it would take 11.11 minutes for it to fill if they worked together.
PAul.</PRE>