D.) A polynomial cannot have a variable in the denominator.
Answer:
C. y +3 = x +3
Step-by-step explanation:
We need to find in below option x has direct variation with y.
We solve for each;
A. 
From above equation we can state that 2 times y is equal to 7 less than 3 times of x.
Hence it doesn't represent direct variation.
B. 
Solving above expression we get;

From above equation we can state that y is equal to 10 more than x.
Hence it doesn't represent direct variation.
C. 
Solving above expression we get;

From above equation we can state that y is equal to x.
Hence it represent direct variation.
D. 
Solving above expression we get;

From above equation we can state that 4 times y is equal to 2 less than 4 times of x.
Hence it doesn't represent direct variation.
Hence the Answer which represent direct variation of x and y is,
C. 
You calculate an answer by multiplying each side by each other. hope this helps.
Answer:
question does not seem complete, from what i know it sounds like he should add up the test scores and divide it by five, that will give him his average which should be his grade, please update question if possible
i hope this helped ;)