Translate each of the following verbal statements into differential equations:

a. The yearly rate of change of S is -20.

b. The daily rate of change of U is 0.35 times U.

c. The yearly per capita rate of change for V is 3 per cent.

d. The hourly rate of change of G is the sum of an inflow of 2.5 and an outflow of 3.2.

e. The annual rate of change of the population P is the sum of births with a per capita birth rate of 0.03, a per capita death rate of 0.05, immigration with a rate of 2500 and emigration with a per capita rate of 0.002.