Question 885097
Sum of the FILL rates.  One pipe fills and the other pipe fills LESS THAN ZERO rate.


x = how long to fill if both pipes are open at the same time


{{{1/8+(-1/16)=1/x}}}
{{{1/8-1/16=1/x}}}
{{{2-1=16/x}}}
{{{1*x=16}}}
{{{highlight(x=16)}}} hours