What is %15 over 200?

To find the percent that 15 is of 200.....just use the calculator...hit the "2nd" button and then key in 15/200. Then hit the "%" key.....it will give you answer in terms of a percent.....

And the answer is  $${\mathtt{7.5}}$$ .

The meaning of your question is not clear.

What percentage is 15 of 200:  7.5%

What is 15% of 200:  15/100*200=30