Question 1121791
{{{ 10*.97 = 9.7 }}} cups of water initially
Let {{{ x }}} = number of cups of 43% water mixture needed
{{{ .43x }}} = number of  cups of water in the 43% mixture
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{{{ ( 9.7 + .43x )/ ( 10 + x ) = .61 }}}
{{{ 9.7 + .43x = .61*( 10 + x ) }}}
{{{ 9.7 + .43x = 6.1 + .61x }}}
{{{ .18x = 3.6 }}}
{{{ x = 20 }}}
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Check answer
{{{ ( 9.7 + 8.6 )/( 10 + 20 ) = .61 }}}
{{{ 18.3/30 = .61 }}}
{{{ .61 = .61 }}}
OK