# 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?

(1) Answers

x - blue pens [latex]\dfrac{21}{x}=\dfrac{3}{1}\\ 3x=21\\ x=7\\\\ 21+7=28[/latex] 28 in total

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