<PRE><B>Question 451460</B>
Let {{{x}}} = gallons of pure water to be added
given:
gallons of soap in 25% solution:
{{{ .25*10 = 2.5 }}} gallons
----------------------
{{{ 2.5 / ( 10 + x ) = .05 }}}
{{{ 2.5 = .05*( 10 + x ) }}}
{{{ 2.5 = .5 + .05x }}}
{{{ .05x =2 }}}
{{{ x = 40 }}}
40 gallons of pure water should be added
check:
{{{ 2.5 / ( 10 + 40 ) = .05 }}}
{{{ 2.5 = .05*50 }}}
{{{ 2.5 = 2.5 }}}
OK</PRE>