I have an Finance teacher who I have had for three years and will write me an amazing letter. I also am getting one letter from a Spanish teacher which will be great. So I thought I was set, until I called a UPenn admission adviser and they told me they highly recommend teacher’s of core subjects to write the letters. Finance is an elective. So should I get one from a science teacher and I am unsure if it will be good or a history teacher who will probably write me a solid letter. Or should I just stick with the finance teacher because she knows me the best and will write the best letter.
Thanks for the help, I plan on applying early and want to get the app in asap because I heard it might help being at the top of the pile come Nov. 1st
In my opinion, you received the definitive answer straight from the source.
okay. Do I go with a decent letter from my chemistry and be balanced or a great letter from my history teacher?
Don’t try to read between the lines. Colleges are not trying to deliberately trip you up. If Penn, or any other school, wants something specific, they will flat out tell you. If they want specific SAT Subject Tests, they will tell you. Similarly, if they want you to have 1 STEM rec and 1 humanities rec, they will tell you. In fact, Penn tells you that is not needed:
Therefore, go with the teachers who will give the best insight; if that’s a Spanish and a history teacher, that is totally fine for Penn.
http://www.admissions.upenn.edu/apply/whatpennlooksfor/teacher-evaluations
Thank you! I will go with the history teacher then. Is it better to have them write about how I am in class and in general or all my extracurriculars. I would think how I am in class because the rest of the app covers the extracurriculars.
It is better that s/he writes about you as a person. 
Feel free to give him/her a copy of your resume, but trust that s/he knows how to write a LoR; you have enough on your plate.