Question 1048731
Let {{{ x }}} = gallons of water needed
{{{ .5 - x }}} = gallons of the 8% solution
{{{ .08*( .5 - x ) }}} = gallons  of fertilizer in the 8% solution
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{{{ .08*( .5 - x ) / .5 = .02 }}}
{{{ .08*( .5 - x ) = .01 }}}
{{{ .5 - x = .125 }}}
{{{ x = .375 }}}
3/8 gallon of water needs to be added
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check:
{{{ .08*( .5 - x ) / .5 = .02 }}}
{{{ .08*( .5 - .375 ) / .5 = .02 }}}
{{{ ( .08*.125 )/.5 = .02 }}}
{{{ .01 = .5*.02 }}}
{{{ .01 = .01 }}}
OK