Busani has 100 cards. There is a whole number from 1 to 100 on each card. No cards have the same number. Busani puts a star on every card that has a multiple of 4 on it. She puts a circle on every card that has a multiple of 5 on it. Write down in order the cards that have a star and a circle on them. What is the third number on your list? Work out how many cards have both a star and a circle on them.