A formal email

From: Francisco Causil [franciscocausil2@gmail.com] 
To: Sarah Muños [saramuños02@gmail.com 
Subject: to request a small favor. 

Dear friend.

 I am writing to you to really help me solve a Mathematical problem. Related to linear algebra, I would like to know if you have some free time to give me some good strategies and so I can clarify the doubts of this subject and that I can easily understand, Because I know that you are good in that field of knowledge since you studied mathematics at a great university in Cartagena.

 I hope you can help. Could you please help me before the other month? Because I have to do an exam I hope to count on your humble help since I do not know anyone with such Skills, my friend Sarah, I remember that you used to emphasize in school in almost all the areas. It would be nice of you to collaborate. Too bad to bother you, I know you have a lot of work to do in the school where you work now. 
Do not worry, I'll pay you for your valuable time if you think so. Reply my message just read it to confirm if you collaborate thanks for your attention my friend.

Sincerely,
 francisco causil.

Thank.