What is the answer to 3/5 x 10/21 in simplest

6/21 I think cause you can't go down any more

First, let's make this easier. Think of 3/5 multiplied by 10/21 as different multiplication problems. First, you should multiply the numerators then the denominators. But before we actually multiply, we can cross simplify.

3       10
_        _ 
5        21    3 divided by 3= 1. 21 divided by 3 is 7. Then you can cross simplify                   again. 5 divided by 5 is 1. 10 divided by 5 is 2. So your                                   multiplication problem has now been put into simpler terms and                       smaller numbers. This makes it easier to solve so you don't have                     to multiply such big numbers together. 

Your new much simpler multiplication problem is 1/1 multiplied by 2/7. Your answer is 2/7 and it has been put into simplest form. 

(Sorry the explanation is so long. Hope this helps!)