Is 12/30 greater or less than 6/10 and how do u know

What I do is converting 12/30 to a fraction with 10 in the button as 6/10,

so if you want to get 10 on the button you divide 30 with 3 and 12 with 3, so

12/30 = 4/10

then I compare it to 6/10

and see that 6/10 is bigger/greater than 4/10 (12/30)