The two angles form a straight line which is equal to 180 degrees. This makes the angles supplemtary.
To find x, add the two angles together to equal 180:
7x + x+20 = 180
Combine like terms:
8x + 20 = 180
Subtract 20 from both sides:
8x = 160
Divide both sides by 8:
X = 20
is the size in wheels on the scale model .
<u>Step-by-step explanation:</u>
Correct Question : Tom has a scale model of his car. The scale factor is 1 : 12. If the actual car has 16-inch wheels, what size are the wheels on the scale model?
We have , The scale factor is 1 : 12. We need to find If the actual car has 16-inch wheels, what size are the wheels on the scale model .Let's find out:
Ratio of size of wheels to actual size of wheels is 1:12 , but actual car has 16-inch wheels So ,
⇒
{ x is size of wheel in scale model }
⇒ 
⇒ 
⇒ 
Therefore ,
is the size in wheels on the scale model .
For this case we have the following system of equations:

To solve, we clear "x" from the second equation:

We substitute "x" in the first equation:

We clear the value of the variable "y":

We look for the value of the variable "x":

Thus, the solution of the system is given by:

Answer:

Option D