Answer: 15
Step-by-step explanation: The common denominator for these 2 fractions is simply the least common multiple for the 2 denominators.
To find the least common multiple or lcm of 3 and 5, we begin by listing the first few multiples of each number.
Multiples of 3
1 x 3 = 3
2 x 3 = 6
3 x 3 = 9
4 x 3 = 12
5 x 3 = 15
We skipped 0 x 3 because our lcm can't be 0.
Next we list the multiples of 5.
Multiples of 5
1 x 5 = 5
2 x 5 = 10
3 x 5 = 15
Notice that 15 appears in both lists so
our least common denominator is 15.