Final answer:
To determine the number of years before the populations of Canton and Holly Springs are equal, set up the equation '7720 + 80x = 3200 + 120x' and solve for x. It would take approximately 18.33 years for the populations to be equal.
Step-by-step explanation:
To determine the number of years before the populations of Canton and Holly Springs are equal, we need to set up an equation using the information given. Let x represent the number of years. The equation for Canton's population would be 7720 + 80x, and the equation for Holly Spring's population would be 3200 + 120x. We can set these two equations equal to each other: 7720 + 80x = 3200 + 120x. Solving for x, we find that it would take approximately 18.33 years for the populations of Canton and Holly Springs to be equal.