IB grades to GPA ? and advice.

<p>I want to major in physics, this is my first year in IB. My subjects are math, physics and chemistry higher level. Economics, English, Arabic standard level and we take extra German sessions daily. I want to apply to universities in the US and they usually require a high GPA. Now our grading system in our school is out of 20. In our school a 16-17/20 in physics for example is equivalent to a 7/7 in IB. But according to the general GPA system a 16-17 is a B or B+. I discussed this problem with our school and they might either consider a 7/7 an A or a grade higher than 17/20 an A. Now i am doing exceptionally well in all of the subjects ( achieving grades higher than 18 ) except with chemistry and English. Which are currently between (14-15). Will this affect my chances of getting admitted greatly when applying to top universities in the US? Should i drop chemistry Higher level for ITGS since it will be easier for me to get grades or is the combination of Physics, Math and chemistry better even though i have 14-15/20 in chemistry? Also when applying do universities require me to send our original grading system? or just the GPA equivalent ? I need advice on what to do.</p>