5. Quarter past 2 is 15 minutes past 2 so it is 2:15
2:15 plus 30 minutes would be 2:45
6. The change you get when you buy something is the amount you pay with minus the cost. If you subtract $2.80 from $5 you get $2.20.
5 - 2.80 = 2.20
It could be 2 one-dollar bill and 2 dimes (1 dime = 10 cents).