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Whit h equation best represents this situation the number 98 increased by an unknown number equal to 120

Grading scale 1 has the following weights- (tests- 50% quiz- 25% homework- 15% final exam- 10%). calculate your final average if your performance in the class is as follows-test grades- {88, 84, 90, 75, 70, 81); quiz grades- {88, 67, 90, 90, 45, 99, 76, 98, 100}; homework- 90; final exam- 75

Ireally don't understand this, i'm really an idiot but i want to know how to figure this out. !