This document discusses solving a system of two equations with two unknowns using substitution. It shows the steps of substituting the value of x from one equation into the other equation to get an equation with only one unknown. This reduces the system to a single variable equation that can be solved for the value of x, which is then substituted back into one of the original equations to find the value of y. The solution to the system of equations in this example is x=6 and y=47.