St. Ives Problem/Rhind Papyrus Variant

Classic Problem
Problem $79$ of the Rhind papyrus, written by some time around $1650$ BCE, concerns:
 * $7$ houses, each with:
 * $7$ cats, each with:
 * $7$ mice, each with:
 * $7$ spelt, each with:
 * $7$ hekat

Solution
Thus we have:

As with the St. Ives Problem, the total can be calculated using the Sum of Geometric Progression: