Answer:
Perimeter of Triangle: 

Step-by-step explanation:
The perimeter is the sum of all of the sides of the triangle.
Hence, the perimeter 
Since the perimeter is 90,
.
Subtract 15 from both sides:


Divide both sides by 6:


Answer:
C
Step-by-step explanation:
sorry if I'm wrong
Answer:
(4, -3)
Step-by-step explanation:
You just divide each coordinate by 3.
<span>6x-2y=-8
-2y =-6x-8
y = 3x+4
y= 3x+4</span>
Second one is correct, that is an identity.
Third one is a contradiction:
6x - 15 = 3 * (2x - 6) ------> 6x - 15 = 6x - 18
Fourth one:
5x - 3 * (x - 4) = 2 * (x - 6) ---> 5x - 3x + 12 = 2x - 12 ---> 2x + 12 = 2x -12
So this is a contradiction as well.