The growth, f(x), in inches per year of a redwood tree less than 30 years old is given by the function f(x)=0.02x^2+x+1, where x represents the number of inches of rainfall per year.
a. Find the growth per year of a redwood tree in a year in which there is 12 inches of rainfall.
b. If the growth of a redwood tree in one year is 10 inches, find the number of inches of rainfall for that year (round your answer to 2 decimal places).