Writing multiple areas of interest in SOP So first let me introduce myself. I am planning to apply for masters in mathematics  in this year. I am student of bsc. 3rd year of Mathematics. Although my initial interest was to study about algebraic number theory, to know about algebraic number theory deeply, i think one should know about commutative algebra also. So I started a readership  on commutative algebra under a professor. But as the time passed I also stared to grow liking for commutative algebra. And now I want to explore more commutative algebra before diving deep into algebric number theory, so here comes the problem. 

In the Sop while applying to foreign is it okay to write about having multiple subject of interest as one is prerequisite of other. Or should I specify one of them. I really want to study algaebric number theory but I also want to know more about commutative algebra. 
Any help will be appreciated. Thanks in advance.
The Statement of Purpose should reflect your interest in your mathematics and give an impression of both you as a scholar and why the department you are applying to should think that you will be successful. As such, you have great freedom in explaining what you find exciting and interesting, and if that includes your desire to look into multiple areas, then that seems like a fine approach to writing a SoP.

In other words, I would not overthink this: Write why you want to go to grad school and why anyone should think that you will succeed there!

(As a comment on the side: I would suggest you spend more time proof reading what you write. There is a typo in the title of your question, and multiple language and grammar mistakes in the question itself. I don't know whether English is your first language, but at the very least typos are completely avoidable; not proofreading what you write just makes you look sloppy and unprofessional.)