Sphere a = 40 cubic inches sphere b = 10 cubic inches how many inches more is the radius of sphere a than the radius of sphere b? round your answer to the nearest tenths. (use π = 3.14.)

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! )