Which equivalent fraction would you have to use in order to add 3/5 to 21\\25

In order to add fractions, the denominators (the bottom numbers) must be the same. We can convert the first fraction of 3/5 to 15/25 by multiplying both the numerator (the top number) and the denominator by 5. Then we have 15/25 + 21/25. To add these fractions, we simply add the numerators together and keep the denominator, which results in 36/25. This reduces to 1 11/25, or 1/44.

Wednesday, February 01 2012
Source: http://www.mathsisfun.com/fractions_addition.html