1. Individuals make socks, which are only valuable in pairs. A pair of socks sells for $10. Since a single sock is pointless, it cannot be sold for a positive price.

Assume that the socks do correspond to right or left feet and that only pairs of one right sock and one left sock can be sold for $10. If there are 4 individuals who each produce a left sock and 5 individuals who each produce a right sock, what is one "core" solution? (You don't need to describe them all, although they all share some things in common. For the answer you only need to give a single allocation that is in the core. It will help to label your layers, maybe r1, r2, l1, l2, etc.)