To multiply these two expressions, we can use the distributive property.

First, let's multiply the terms in the first expression by each term in the second expression:

(2/5а 3/7б) + (2/5а 2/5а) - (3/7б 3/7б) - (3/7б 2/5а)

Now, let's simplify these terms:

(6/35аб) + (4/25a^2) - (9/49b^2) - (6/35ab)

Now, let's combine like terms:

(6/35ab - 6/35ab) + (4/25a^2) - (9/49b^2)

This simplifies to:

0 + (4/25a^2) - (9/49b^2)

Therefore, the product of (2/5а-3/7б) and (3/7б+2/5а) is:

4/25a^2 - 9/49b^2