Question 588168
Let {{{ x }}} = pounds of  yarn with 15% wool needed
{{{ .15x }}} = pounds of wool in the 15% yarn
{{{ .6*16 = 9.6 }}} pounds of wool in the 60% yarn
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{{{ ( .15x + 9.6 ) / ( x + 16 ) = .33 }}}
{{{ .15x + 9.6 = .33*( x + 16 ) }}}
{{{ .15x + 9.6 = .33x + 5.28 }}}
{{{ .33x - .15x = 9.6 - 5.28 }}}
{{{ .18x = 4.32 }}}
{{{ x = 24 }}}
24 pounds of  yarn with 15% wool is needed
check:
{{{ ( .15x + 9.6 ) / ( x + 16 ) = .33 }}}
{{{ ( .15*24 + 9.6 ) / ( 24 + 16 ) = .33 }}}
{{{ ( 3.6 + 9.6 ) / 40 = .33 }}}
{{{ 13.2 / 40 = .33 }}}
{{{ 13.2 = .33*40 }}}
{{{ 13.2 = 13.2 }}}
OK