Question 799226
Let {{{ x }}} = cups of o.j. to be added
{{{ .1*50 = 5 }}} cups of o.j. in 50 cups of punch
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{{{ ( x + 5 ) / ( x + 50 ) = .2 }}}
{{{ x + 5 = .2*( x + 50 ) }}}
{{{ x + 5 = .2x + 10 }}}
{{{ .8x = 5 }}}
{{{ x = 6.25 }}}
6.25 cups of o.j. must be added
check:
{{{ ( x + 5 ) / ( x + 50 ) = .2 }}}
{{{ ( 6.25 + 5 ) / ( 6.25 + 50 ) = .2 }}}
{{{ 11.25 / 56.25 = .2 }}}
{{{ 11.25 = .2*56.25 }}}
{{{ 6.25 = 6.25 }}}
OK