Answer:
The simplified expression is 28/45a².
Explanation:
To simplify (7/9a)(4/5a), we can multiply the numerators together and the denominators together, which gives:
(7/9a)(4/5a) = (7 x 4) / (9a x 5a) = 28 / 45a²
Therefore, the simplified expression is 28/45a².