Question

Write the pairs of fractions as a pair of fractions with a common denominator
3/10 and 2/5
1/3 and 3/4

Answer 1

Technically the first pair could be:
$\frac{3}{10}$ and $\frac{4}{10}$
IF that isn't an answer choice,
$\frac{6}{20}$ and $\frac{8}{20}$
Is correct as well
The second would be:
$\frac{4}{12}$ and $\frac{9}{12}$

Answer 2

3/10 and 2/5 would turn into 3/10 and 4/10. You don't have to change 3/10 because that is the common denominator.

1/3 and 3/4 would turn into 4/12 and 9/12 because 3 can go into 12 four times, so you do 1 x 4 which gives you a fraction of 4/12. You do the same with 3/4 too.