An investment of d dollars at k percent simple annual interest yields…

An investment of d dollars at k percent simple annual interest yields $500 over a 2 year period. In terms of d, what dollar amount invested at the same rate will yield $2,000 over a 4 year period?

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 #525