Should I take the ACT or SAT or both?

Chemistry and geometry are bad subjects in general. Take both.

Take both and don't have the scores sent to you.  My score was stolen from me... someone lied and said ACT mixed up our scores which they knew it was not true but they said they had to resolve it by giving both of us the lowest of the two scores...it made my score drop over twelve points.  Remember the test is multiple choice...the answers are there if you know the math formulas just plug the answer in and try.

you should take both 

Just take both it can’t hurt 

Chemistry and geometry are bad subjects in general. Take both.

Either one is find. There is no point in taking both. These two tests have become much more alike in recent years, and most US universities are happy to accept either one.  Some very selective universities also as for SAT II Subject tests, but if you aren't applying to those schools, you don't need to take those either.  

You don’t need to take both.  Do a brief search research on the material in both of them. Which one do you feel you would do best in.  

It really depends on where you want to go to college. Take both of you want to open your choices broadly. Usually, if your plan is only to apply to one of your state’s public universities (Example: Louisiana State University (LSU)) you really only need the ACT but you really need to check what the schools you’re interested in require. You don’t want to be left out of contention where you want to go because you didn’t take the test.