Question

using a common denominator to write an equivalent fraction for 3/7?

Answer 1

6/14

Multiply both 3 and 7 by 2, this gives you equivalent fractions (there are more possible equivalent equations of course)

Answer 2

I'm not sure exactly what you are trying to ask, but you can multiply the numerator and denominator by any number and it will stay the same value fraction, as long as you are multiplying them both by the same number.