How old was Reu when he died?
Reu lived 239 years, from 2217 BC to 1978 BC.
Reu died at 239. The chart places his birth at 2217 BC and his death at 1978 BC, on the Ussher chronology it follows. Lifespans have now halved since the Flood. (Gen. 11:20-21)
See it in context
A date means more beside its neighbours. The chart puts this answer in place next to everything happening around it — biblical and world history across the same six thousand years.
Now see where it sits
Everything on this page has a place on one 45×37″ chart — and once you can see what came before and after it, it stops being a fact and starts being a story you can follow.