The answer to me look's like C is the correct answer so nice job!
8+2x=6x
subtract -2x on both sides
8=4x
Divide by 4 on both sides
2=x
all you need is the story :)
Given

consider substituting
to get a proper quadratic equation,

Solve for
; we can factorize to get



Solve for
:

The first equation has no real solution, since
for all non-zero
. Proceeding with the second equation, we get

If we want to find all complex solutions, we take
so that the first equation above would have led us to

Volume is height times length times width
V = 15/28 ft^3
h = 11/2 ft
l = 5/7
w = ?
So the unsolved equation is:
V = h × l × w
Separate the w by diving both sides by h and l:

Then plug in the numbers:

Which, with the fractions flipped, equals:


The width of the box is 3/22 ft