We can use the equation 15,400 - 325x = 775. This is because the current population is 15,400, and 325 people leave yearly. X represents the amount of years, and we need to solve x to figure out how many years for the population to fall to 775.
We need to isolate x. We can do that by subtracting 15,400 from both sides. This gives us -325x = -14,625. Next, we need to divide both sides by -325. This gives us x = 45.
We can plug 45 into x to check our answer. 15,400 - 325(45) = 775. 15,400 - 14,625 = 775.
It will take 45 years for the population to fall to 775 people.
