Varma can read a book in k minutes

Varma can read a book in k minutes. What part of the book can he read in 5 minutes?(k>8)

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 #9395