You need to find the question mark. Let's call this question mark, x.
3 4/5 ÷ x = 2 5/7
To get x, you need to multiply 2 5/7 and 3 4/5.
Then, make them into improper fractions.
(7 × 5) + 2 = 37/7 (It stays over 7)
(5 × 3) + 4 = 19/4 (It stays over 4)
37 × 19 (Just multiply across)
7 4
703
28
Then, make this into a mixed number.
703 ÷ 28 = 25.1 or 25 1/10