Tuesday, September 27, 2022

Liar's algebra

Robbie, Gary, and Jason work at a shop that sells pens, erasers, and pencils.
Robbie says: “Seven pens and five erasers cost the same as six pencils.”
Gary says: “Four pens and nine pencils cost the same as five erasers.”
Jason says: “Six pencils and three erasers cost the same as four pens.”

Only one is lying. Can you tell us who?

From Alex Bellos's Monday puzzle.

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