Samuel went to the grocery store and purchased cans of soup and frozen dinners.
Each can of soup has 300 mg of sodium and each frozen dinner has 450 mg of
sodium. Samuel purchased 5 more frozen dinners than cans of soup and they all
collectively contain 6000 mg of sodium. Write a system of equations that could be
used to determine the number of cans of soup purchased and the number of frozen
dinners purchased. Define the variables that you use to write the system.