Answer:
Subtraction Property of Equality
Step-by-step explanation:
you should subtract both side with 7 first.
For this case we have that by definition, the density is given by:

Where:
M: It is the mass of the diamond
V: It is the volume of the diamond
According to the data of the statement we have:

So the volume is:

Thus, the volume of the diamond is approximately 
Answer:

The answer should be A 160
It could be written as 8w the simplified version of the example.
Or you could write it as 2(3w + w) which is 2 time the length and width.