Question 957722
Let {{{ x }}} = gallons of 10% solution needed
{{{ .1x }}} = gallons of salt in 10% solution
{{{ .2*15 = 3 }}} gallons of salt in 20% solution
---------------------
{{{ ( .1x + 3 ) / ( x + 15 ) = .16 }}}
{{{ .1x + 3 = .16*( x + 15 ) }}}
{{{ .1x + 3 = .16x + 2.4 }}}
{{{ .06x = .6 }}}
{{{ x = 10 }}}
10 gallons of 10% solution are needed
check:
{{{ ( .1x + 3 ) / ( x + 15 ) = .16 }}}
{{{ ( .1*10 + 3 ) / ( 10 + 15 ) = .16 }}}
{{{ 4 / 25 = .16 }}}
{{{ 4 = 4 }}}
OK