The equations

and

are really the same, we're just setting
, or
.

So we get

Answer:
The solution for this system is: 
Step-by-step explanation:
The problem states that we have to solve this system by the elimination method
In the elimination method, we transform the system in such a way that one variable can cancel each other. With this, we find the result of the other variable. Then, we can replace the variable we found in any of the equations, and we have the value of the variable that we had initially canceled.
In this problem, we have the following system:


If we add equations 1) and 2), the variable x is going to be eliminated





Now, we can replace the value of y in any of the equations, to find x:
I will replace in equation 2)





The solution for this system is: 
Answer:
6,226 tiles of 9 in are needed to cover an area of 400 square feet
Step-by-step explanation:
Let
A -----> an area in square feet
t(A) ---> the total number of 9 in. tiles needed
we have

For A=400 ft^2
substitute in the equation and solve for t


That means -----> 6,226 tiles of 9 in are needed to cover an area of 400 square feet
Answer:

Step-by-step explanation:
"4 times the sum of 2 and y".
<h3>Hope it is helpful...</h3>