Find four rational numbers between 3/4 and 2/5.

To find 4 rational numbers between 3/4 and 2/5, we need to make these rational numbers with the same denominator.

So, 3/4 can be written as 3/4 x 5/5 = 15/20

2/5 can be written as 2/5 x 4/4 = 8/20

Now, We have many rational numbers between 15/20 and 8/20.

Rational numbers between 3/4 and 2/5 are 9/20, 10/20, 11/20, 12/20, 13/20, 14/20.