Answer:
b^2
------
2a
Explanation:
-6ab^3 10b
-------------- * -----------
5a -24 ab^2
Rewriting
-6ab^3 10b
-------------- * -----------
-24 ab^2 5a
Canceling like terms
b 2b
-------------- * -----------
4 a
Canceling the 2 and 4
b b
-------------- * -----------
2 a
b^2
------
2a