Question 806324
The gallons of salt in the 15% solution is
{{{ .15*15 = 2.25 }}}
The gallons of salt in the 29% solution is
{{{ .29*20 = 5.8 }}}
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{{{ ( 2.25 + 5.8 ) / ( 15 + 20 ) = 8.05 / 35 }}}
{{{ 8.05 / 35 = .23 }}}
{{{ .23*100 = 23 }}}
The % salt  is 23%