Help with fractions magic square!

Hi,

I am new here and am in first year of high school. I am ok with maths but when it comes to puzzles i'm easily bamboozled. This is a fractions puzzle and since most of you are much more experienced with maths than I am, this shouldn't be hard. First off, I *can* add/subtract/multiply/divide fractions, but I can't solve a magic number square. (In case you don't know, in a magic number square the numbers in every row, column and diagonal line must add up to the same thing, in this case 7 1/2. {7 and a half, i can't make fractions on a forum}) Here is my magic square:

Code:

` _____________`

|2 7/8| ? | ? |

_____________

|2 1/4| ? | ? |

_____________

|2 3/8| ? |2 1/8|

______________

I have been trying for ages to get this but I just can't figure it out! (Headbang) (Headbang)

This is homework for tomorrow, so I really need an answer (please!)

Thank you so much for your help.