Algebra 1 problems. Please help Today, it's Urgent?

Ok, so I need some help with these Algebra 1 problems. I just can't figure them out, and my text book doesn't show me how to do these problems. I need the answers today, so please help me if you can. I know that this is last minute, but it is urgent. Thanks so much in advance. Here are the problems:

9.) Two numbers, 4 and a, have a geometric mean of 12.

Find the value of a.

10.) Two numbers, 3 and a, have a geometric mean of 9.

Find the value of a.

11.) Solve the equation by completing the square:

x^2 + 2x = 3

12.) Solve the equation by completing the square:

x^2 + 8x = 14

15.) Find the distance between the two points:

(5,8), (2,4)

16.) Find the distance between the two points:

(7,12), (1,4)

19.) You and a friend go biking. You bike 12 miles north and

2 miles east. What is the straight-line distance from your

starting point? Round answer to the nearest hundredths.

22.) A company had sales of $500,000 in 1996 and sales of

$720,000 in 1998. Use the midpoint formula to find the

company's sales in 1997.

Please help! The sooner you reply, the better. Thanks a lot!