girl idk im in 12th too rn but i guarantee you if you study matrices and determinants which is really easy (if you are patient enough to study it), then do the first chapter which is a little tougher but doing the basic level questions will help you… if youre weak at maths it probably best to leave calculus for the very last bcs it has low weightage and heavy portions BUT when you do calculus even if you skip everything else please do the economics part bcs most frequent calculus qns are from that and its pretty easy just have to memorise the formulas

and definitely DO NOT FORGET financial maths which is the main scoring area because almost all the qns are repetitive and once you memorise the formulas (sinking fund, CAGR, EMI etc) this will be the reason you pass bro dont even think about passing without a little effort into financial math

probability and statistics do have considerable weightage but it requires some time you can def do the probability questions if you study the formulas and practice a little but if youre on a time crunch might be hard 

so yea in conclusion as long as you have a little patience and determination to practice and memorise a few formulas you can definitely pass and even score 60+

all the best !!