Two vehicles driving in the same direction, down a highway at 100 km/h. A passenger in the leading car sounds a 1000 Hz whistle. What frequency will a passenger in the following car hear?

The length and width of a rectangle are consecutive even integers the area of the rectangle is 120 squares units what are the length and width of the rectangle

This is about circle theorems. someone asap : (

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )