I have the same question too so I need help on it
It’s A
Because I just did it
Since 216 is the cube of 6, 64 is the cube of 4 and x^3 is the cube of x, we have

so the expression is the sum of the cubes of 6x and 4
L=k/r^2,
r^2 is the denominator cause L varies inversely with the square of distance
The answer is B
Simplify 9 - 7x - 7x to 2 - 14x
2 - 14x = 4
Subtract 2 from both sides
-14x = 4 - 2
Simplify 4 - 2 to 2
-14x = 2
Divide both sides by -14
x = -2/14
Simplify 2/14 to 1/7
x = -1/7