What is the common denominator 2/5 and 2/3

The common denominator would be 15 since 5 times 3=15.

The common denominator would be the first number divisible by both 3 and 5. In this case, it's 15. 3x5=15. After getting the common denominator, you multiply 2 by 3 and 5 respectively, giving you 6/15 and 10/15 to work with as you need.