Answer:
10 years
Step-by-step explanation:
Let c and s represent the populations of Canyon Falls and Swift Creek, respectively. For time t in years, the respective populations are ...
c = 22500 -740t
s = 15200 +1500t
We want to find t when s = 2c.
s = 2c
15200 +1500t = 2(22500 -740t)
2980t = 29800 . . . . . add 1480-15200, simplify
29800/2980 = t = 10 . . . . divide by the coefficient of t
The population of Swift Creek will be double that of Canyon Falls in 10 years.