You multiply both the numerator and the denominator by the same number (but not 1 or 0), but don't simplify. 3/10 is your fraction, and you could multiply the top and bottom numbers by 2 to get 6/20.

You multiply both the numerator and the denominator by the same number (but not 1 or 0), but don't simplify. 3/10 is your fraction, and you could multiply the top and bottom numbers by 2 to get 6/20.