Mr. and Mrs. Horner will be visiting the museum with their three children. Tickets cost $25 for adults and $15.50 for children. How much will it cost for the whole family to visit the museum?

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! )