Wind Power!

An airplane is riding in the wind. Halfway through, the plane increases speed by 15 m.p.h. The time takes three hours and the distance travelled is 500 miles. What was the original speed of the airplane?

Time yourself!

To start, time yourself to see how long it takes for you to calculate the answers. Post your time in the comments! And do not use a calculator!
(Note: #1 does not need to be written out in full.)

1. 2^100 - 2^99


2. 6! + 7!


3. 198/6


4. 678+789


5. 100^(-1/2)


6. 1234+2345+3456+...+6789


7. (2^15)(5^16)


8. 155^2 - 154^2

Welcome!

This is a blog designed for your mathematical needs! I will post problems as well as give "lectures", if you will. Have fun!