Amy and Jodie #3

This note was also found with the other two.
It was in an envelope addressed to "Amy!", on the reverse of the envelope "From Tracy" and "Read as soon as possible (other words when you are alone)" was also written.
The letter reads...

Dear Amy,
Hi. On Tuesday you asked me if Donna knew your maths score, well, yes she does know, I'll show you the letter she wrote me. Don't forget, you have swarn to secrecy. If Donna finds out that I wrote this in your letter I'll tell Jodie what you told me. I know you like Donna better than me but still don't sqeel on me. Anyway good luck in your operation Love tracy.
P.S. She said you got 46%
bye.
P.T.O.
P.P.S. I'm really a loyal friend but you asked me to do this task before she told me your score so i did.