Solve and state any extraneous solutions

If f(x)=2x-6 and g(x)=3x+9, 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

For a function f(x), a) if f(7) = 22 then f^-1(22) = b) f^-1(f(c)) =