Mary needs to reflect point B, which is located at (4, 9), over the y-axis. Write the coordinate that is a reflection of point B over the y-axis? Include ( ) around your coordinate.

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! )

Determine if this is a solution to the system

The diameter of the moon is about 3500 km. approximate the surface area of the moon using the formula for the surface area of a sphere, s = 4πr^2. write your answer in scientific notation.