Posted by **Joe** on Tuesday, January 19, 2010 at 6:42pm.

How would I solve these two problems. (We have to simplify our answer)

5/7 divided by 8/21

12/7 divided by 9/21

- Math-Fractions -
**Reiny**, Tuesday, January 19, 2010 at 6:54pm
I will do the first, you do the second

5/7 divided by 8/21

= (5/7)÷(8/21)

= (5/7)(21/8)

= 15/8 , (the 7 cancelled into the 21)

- Math-Fractions -
**Kelly**, Tuesday, January 19, 2010 at 7:00pm
I'd like to learn this. How did you get 15/8. Did you multiply 5 by 3 to get that?

- Math-Fractions -
**Reiny**, Tuesday, January 19, 2010 at 7:03pm
yes, to multiply fractions, you multiply the numerators, and you multiply the denominators.

e.g.

2/3 x 5/7 = 10/21

in your question of

(5/7)(21/8)

I had 105/56

= 15/8 after dividing top and bottom by 7

- Math-Fractions -
**Kelly**, Tuesday, January 19, 2010 at 7:12pm
that's cool. Thanks

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