Answer:
The answer is

Why? Below I explain
Step-by-step explanation:
That formula has three variables a, b and c.
So, a = 2, b = 3 and c = -1
Because the formula is written like

If you are just dividing percent's, then each grade would have 12.5 percent.
65 is the asnwer hope i helped
Answer:
Notebooks= 8.75
computer bags=74.95
Amount with tax = Approximately 89.559