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
Add answer
Sign in
Sign up