A pharmaceutical company received …12; million in sales of generic equivalent of…

A pharmaceutical company received $2 million in royalties on the first $12; million in sales of generic equivalent of one of its products and then $4 million in royalties on the next $48 million in sales. By approximately what percent did the ratio of royalties to sales decrease from the first $12 million in sales to the next $48 million in sales?

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 #776