If Re.50 amounts to Rs.250 over a period of 30 years

If Re.50 amounts to Rs.250 over a period of 30 years. What is the rate of simple interest?

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 #9769