Please Help - Let f(x)=x−1/x+1.

(a) Evaluate f^−1(3)=

(b) Evaluate (f^−1)′(3)=

At a pizza shop 70% of the customers order a pizza 25% of the customers order a salad and 15% of the customers order both a pizza and a salad if s customer is chosen at random what is the probability that he or she orders either a pizza or a salad