annamo137
annamo137 annamo137
  • 20-01-2015
  • Mathematics
contestada

A teacher had 21 red pens. If the ratio of red pens to blue pens she owned was 3:1, how many pens did she have total?

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konrad509
konrad509 konrad509
  • 20-01-2015
x - blue pens

[tex]\dfrac{21}{x}=\dfrac{3}{1}\\ 3x=21\\ x=7\\\\ 21+7=28[/tex]

28 in total

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