The function f(x)=60_e^-0.8x+40 describes the percentage of information, f(x), that a particular person remembers x weeks after learning the information.

a) substitute 0 for x and, without using a calculator, find the percentage of information remembered at the moment it is first learned

b) substitute 1 for x and find the percentage of information that is remembered after 1 seek.

c) find the percentage of information that is remembered after 4 weeks

d) find the percentage of information that is remembered after one year (52 weeks)

(round to the nearest decimal as needed)