A seller uses 840gm in place of 1kg to sell his goods

A seller uses 840gm in place of 1kg to sell his goods. Find his actual % profit or loss, when he sells his article his article on 4% gain on cost price?

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #86056