Answer:
4ab² + 20b - 3a
Explanation:
This question most likely asks us to simplify the expression, as factoring is not possible...
(ab² + 13b - 4a) + (3ab² + a + 7b),
ab² + 13b - 4a + 3ab² + a + 7b,
ab² + 3ab² + 13b + 7b - 4a + a,
Solution : 4ab² + 20b - 3a