Simplifying Rational Expressions / Distance (Word) Problems

Hi, I need help on trying to solve these two equations:

"Express in simplest equivalent form."

http://img225.imageshack.us/img225/4...e15855bsn8.jpg

and

http://img266.imageshack.us/img266/3...e15855ezh6.jpg

Now for the word problems... I'm having trouble with these distance problems since I don't know where to place which numbers... so it'd be great if someone could show me each step and explain why the numbers are there... I'd appreciate it. =)

"A plane takes the same amount of time to fly 1500 km at 100 km/h below its top speed as it takes to fly 1250 km at 200 km/h below its top speed. What is the plane's top speed, in kilometers per hour?"

"David flew 300 km on a commuter plane, then 2000 km on a passenger jet. The passenger jet flew twice as fast as the commuter plane. The total flying time for the journey was 3 1/4 hours. What was the speed of each plane in kilometers per hour?"

"Nadia and Kyle shared the driving on a 1250 km trip from Edmonton to Vancouver. Nadia drove for 6 hours and Kyle drove for 8 hours. Nadia drove 10 km/h faster than Kyle. How fast did Kyle drive?"

Thanks, any help is appreciated!