Parallel means they have the same slope.
The given equation has a slope of 3. Slope intercept equation: y = mx + b
a. 6x + 2y = 12
Subtract 6x from both sides.
2y = - 6x + 12
Divide both sides by 2.
y = -3x + 6 Not parallel
b. -3x + y = 8
Add 3x to both sides.
y = 3x + 8 Parallel
c. 3y = 9x
Divide both sides by 3
y = 3x Parallel
d. y = -1/3x Not parallel
B and C are parallel
For this case we have the following expression:

We must evaluate the expression when:

Substituting the values we have:

Equal signs are added and the same signs are placed.

Different signs are subtracted and the sign of the major is placed:

Finally we have to:

Answer:
A and C because they dont have repeating values
50 is the answer bc mid point is the middle