What will be the coordinates of n after a 90 degree counterclockwise rotation around the origin?

What is the simplified form of (3.25x10^3)(7.8x10^6) written in scientific notation?

What is the slope of the line shown below?

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! )