What's the next letter? y b w d u f

Jackie purchased 3 bottles of water and 2 cups of coffee for the family for $7.35. ryan bought 4 bottles of water and 1 cup of coffee for his family for 7.15. how much does each bottle of water cost? how much does each cup of coffee cost?

If a baby uses 15 diapers in 2 days, how many diapers will the baby use in a year?

What are two numbers that add up to -9 and multiply to -10 best answer gets branliest and 100 extra points