Question 1081979
Let {{{ x }}}  = liters of water to be added
{{{ ( 10*10 + 20*30 ) / ( 30 + x ) = 1 }}} dollars/liter
( I think they are assuming that the added
water does not add to the cost )
{{{ 700 / ( 30 + x ) = 1 }}}
{{{ 30 + x = 700 }}}
{{{ x = 670 }}}
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The ratio of water to milk needs to be
{{{ 670/30 = 22.33 }}}
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