Ateacher had 21 red pens. if the ratio of red pens to blue pens she owned was 3: 1 how many pens she she have total

The answer is - 28 - because 21divided by 3=7 (I got 3 by 3:1) so we have to times 7 to 1 =7 (I got 1 by 3:1)(Its similar to fractions but not really). Hope this helps

She would have 28 pens total because the ratio is 3:1, but that is the simplified ratio. So somehow they simplified 21 to 3. 21 divided by 3 is 7. So they simplified 21 by dividing it by 7. That means they divided the # of blue pens by 7 also. Therefore, you would multiply 1 by 7 to get 7. So she had 21 red pens and 7 blue pens. 21+7=28. Therefore she has 28 pens total.