A solid in the shape of a regular tetrahedron had uniform density and a mass of 1 kg. It was mutilated by the removal of its vertices, each made by a planar cut, parallel to its opposite face. The solid now has eight faces, whose areas are 1, 2, 3, 4, 5, 6, 7 and 8 square units, in some order. What is the area of its original faces? What is the mass of the resulting solid?