D because 3/4 is .75 so 7.75 divided by .75 equals 10.333333333333333
The common solution by graphing will be.. x=1
Answer:

Step-by-step explanation:
we know that
The length of the side, s, of a cube with a surface area, SA is equal to the formula

Step 1
Find the length of the side, s, of a cube with a surface area of 
we have

substitute in the formula


Step 2
Find the length of the side, s, of a cube with a surface area of 
we have

substitute in the formula


Step 3
Find the difference of the length sides

Let the unknown number be
.
Then the opposite of this unknown number will be
.
It is given to us in the question that when this unknown number,
is increased by 9, or in other words when 9 is added to this unknown number,
, then this becomes 5 times it's opposite, which is
.
Thus, from the given condition in the question, the equation we get is as:

We will solve this by isolating
as:



Thus the required number is -1.5