What does the y-intercept of this function represent?

Take a look at the graph. We can see that the horizontal axis tells us the number of years since the city was founded. 

Y-intercepts happen at x = 0. So, let's think about what x = 0 means on the graph. This would be "0 years since the city was founded" or the same time the city was founded.

In other words, the y-intercept of this function represents the initial population (the population when the city was first founded).

No he does not because he can only cover 12 square feet from 15 square feet which he will still need 3 more. this is because if 3×5=15 square feet and 15-12=3 which thats the answer