What number adds 10 and multiplies 21

Sasha drank 8 bottles of water everyday for a week. how many bottles of water did she drink in total?

Julie goes to the sports store and spends $40.50 before tax. she buys a pair of shorts for $21.75 and 3 pairs of socks that each cost the same amount. how much does each pair of socks cost? $$

If i had 1234 apples and 1 banana what is the total amount