On a certain farm the ratio of horses to cows is 6:1

On a certain farm the ratio of horses to cows is 6:1. If the farm were to sell 15 horses and buy 15 cows, the ratio of horses to cows would then be 3:1. After the transaction, how many more horses than cows would the farm own?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #5410