A man is 30 years older than his son

A man is 30 years older than his son. In two years, his age will be twice the age of his son. The present age of the son is

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 #178