let's say i had 90% on my exams, worth a total of 30%. Also, on hw i have a total of 85% which is worth a total of 40%. i want to know what i need to get on the final if the final is worth 30% of my grades? 90% is an A in the class.

(.30)*(.90) + (.40)*(.85) + x = .90

i thought it would be something like that, but it doesnt seem correct