<PRE><B>Question 699001</B>
There is no change in the quantity of acid
{{{ .3*30 = 9 }}} liters of acid in 30% solution
Let {{{ x }}} = liters of water to be added
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{{{ 9 / ( x + 30 ) = .2 }}}
{{{ 9 = .2*( x + 30 ) }}}
{{{ 9 = .2x + 6 }}}
{{{ .2x = 3 }}}
{{{ x = 15 }}}
15 liters of water must be added
check:
{{{ 9 / ( 15 + 30 ) = .2 }}}
{{{ 9 / 45 = .2 }}}
{{{ 9 = .2*45 }}}
{{{ 9 = 9 }}}
OK
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