How do i go about solving this problem?

For f(x)=2x+3 and g(x)=x^2- 8 find (f+g) (x)

Organic apples are on special for $1.50 per pound. does total cost vary inversely or directly with the number of pounds purchased? find the cost of 3.4 pounds of apples. a. inversely: $5.10 b. directly; $5.10 c. inversely: $2.27 d. directly; $2.27

Mr.walker is looking at the fundraiser totals for the last five years , how does the mean of the totals compare to the median?