C. 4x + y = 21
4(3) + 9 = 21
12 + 9 = 21
21 = 21
Answer: 
Step-by-step explanation:
We have given the numbers = 2,0,1,9
We can use addition and subtraction operation to the given numbers such that the answer will be equals to 6.
We can add 2 ,0 and 1 and then subtract from 9 , we will get 6.
So the required expression can be

hence, the required expression can be 
Well, let's see how it'll effect your grade...
75% ÷ 90% = 0.83
0.83 x 100 = 83%
It would effect your grade by 7 percent, lowering it to 83%
I hope this helps!
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