Ok Im in business calculus and I have a test on thurs. Im having some probs on my review was wondering if someone could help me solve these. some seem easy I just cant figure them out maybe someone can show me an easy step

1. BLAH BLAH type of products are given by S(t)=60-80e^-.1t where t represents time in years. Find the rate of cange i n sales at the time when t=3

2. Diffrentiate

Find f'(x) for f(x)= x/7x-5?

3. Find f'(x) for f(x)8e^+4ln(x^3)