cost, revenue, marginal and total etc

Got a couple of questions i can't seem to asnwer, this seemed the best forum for them.

Quote:

*The demand and marginal cost functions for a firm’s product are given by the following functions:*

Q = 48 – 2P

MC = 3Q – 8

Where Q = quantity demanded

P = price per unit of the product

MC = marginal cost

1 Determine the total revenue and marginal revenue functions.

2 Determine the profit maximising output and price.

3 If the fixed cost of production is 25, determine the total cost function, the total cost of producing the profit maximising output and the maximum

profit.

and

Quote:

*The average cost and demand functions for a firm’s product are given by*

the following functions:

AC = - 100 + 15 Q

Q = 30 – 0.05 P

Where Q = quantity demanded

P = price per unit of the product

AC = average cost

1 Determine the total cost and marginal cost functions.

2 Determine the total revenue and marginal revenue functions.

3 Determine the profit maximising output and price, and the maximum profit.

4 Suppose that the fixed cost of production rises by 50, determine the

effect on the total cost and marginal cost functions, the total cost of

producing the profit maximising output and the maximum profit.

Any help is really appreciated. My test is coming up soon.