A population P is a function of time t that had 5000 when t=0 can be written P(t)= 5000+B(t)-D(t). B(t) is the number of births since t=0 and D(t0 is the number of deaths since t=0. suppose at a given instant B=800 and dB/dt=100, and D=1000 and dD/dt=85. What is P? What is dP/dt?
P=5000+B(t)-D(t)
dP/dt=dB/dt - dD/dt
dP/dt=100-85=15 at that time
P=5000+800-1000=48OO
This is pretty basic, as is learning to spell calculus.