The best way to find it is to reduce each ratio you work with to its
lowest terms,and see which ones are equal. To reduce a ratio to its
lowest terms, divide each number by their greatest common factor.
First, the one that you're trying to match: 49:35 .
The greatest common factor of 49 and 35 is 7 .
Divide each number by 7 . . . 7:5 . . . that's what you have to match.
7:4
Their greatest common factor is ' 1 '.
No help at all, and this one is not it.
14:25
Again, their greatest common factor is '1 '.
No help at all, and this one is not it.
21:15
Their greatest common factor is ' 3 '.
Divide both numbers by 3 . . . 7:5 .
That's it !