Holiday homework strikes again!

1) A wine merchant buys 50 cases of wine. He pays full price for half of them but gets a 40% discount on the remainder. If he paid a total of $2260, how much was the full price of a single case?

2) A rectangular courtyard is three times as long as it is wide. If the perimeter of the courtyard is 67 m, find the dimensions of the courtyard.

3) Three girls are playing Scrabble. At the end of the game, the total of their scores adds up to 504. Annie scored 10% more than Belinda, while Cassie scored 60% of the combined scores of the other two. What did each player score?

4) The mass of a molecule of a certain chemical compound is 2.45 x 10^{-22}g. If each molecule is made up of two carbon atoms and six oxygen atoms and the mass of one oxygen atom is (1/3) that of a carbon atom, find the mass of an oxygen atom.

Any help would be much appreciated.