Answer:
The constant of variation is 3
Step-by-step explanation:
Given.


And y is directly related to x
∝ 
Here k is constant of variation

--------------(1)
Put the
and
value in equation 1.


So, the constant of variation is 3.
Answer:
The solution of this system of equations is (3 , -8)
Step-by-step explanation:
The given system is
x + 2y = -13
12x + 5y = -4
We make x the subject of the first equation and put it into the second:

We put this expression for x into the second equation
12(-13-2y)+5y=-4
-156-24y+5y=-4
-24y+5y=-4+156
-19y=152
y=-8
We substitute y=-8 into x=-13-2y to get:

The solution of this system of equations is (3 , -8)