Question 1041595
Let {{{ x }}} = gallons of 1% solution needed
{{{ .005*100 = .5 }}} gallons of pure pesticide initially 
in the 300 gallon tank
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{{{ ( .01x + .5 ) / ( x + 100 ) = .008 }}}
{{{ .01x + .5 = .008*( x + 100 ) }}}
{{{ .01x + .5 = .008x + .8 }}}
{{{ .002x = .3 }}}
{{{ x = 150 }}}
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150 gallons of 1% solution needs to be added
check:
{{{ ( .01*150 + .5 ) / ( 150 + 100 ) = .008 }}}
{{{ ( 1.5 + .5 ) / 250 = .008 }}}
{{{ 2 / 250 = .008 }}}
{{{ .008 = .008 }}}
OK