Answer:

Step-by-step explanation:
Let
x ----> 3-room apartments
200-x ----> 4-room apartments
we know that
To find out how many rooms are there in the complex, sum the number of 3-room apartments multiplied by 3 plus the number of 4-room apartments multiplied by 4
so

Apply distributive property

Combine like terms

Step-by-step explanation:
hope this helps........
Isolate the variable by dividing each side by factors that do not contain the variable.
2x=2x-4y+16
2x-16=2x-4y
-4y would have to equal -16
Therefore Y=4
The answer is on the picture below