Question 846757
Let {{{ w }}} = gallons of water she must add
{{{ .4*2 = .8 }}} = gallons of bleach in 40% solution
------------------
{{{ .8 / ( 2 + w ) = .15 }}}
{{{ .8 = .15*( 2 + w ) }}}
{{{ .8 = .3 + .15w }}}
{{{ .15w = .5 }}}
{{{ w = 3.333 }}}
She needs to add 3 and 1/3 gallons of water
---------------
check:
{{{ .8 / ( 2 + w ) = .15 }}}
{{{ .8 / ( 2 + 3.333 ) = .15 }}}
{{{ .8 = .15*5.333 }}}
{{{ .8 = .8 }}}
OK