According to the given data we have the following system of equation:
1) 7x—3y=8
2) y=3x
Therefore, in order to solve the system by substitution, we would substitute the variable y of the first system of equation with the variable y=3x.
So:
7x—3y=8
=7x -3(3x)=8
=7x -9x=8
-2x=8
x=8/-2
x=-4
So, if x=-4, then y would be calculated as follows:
y=3(-4)
y=-12
Therefore, the values of x and y would be x=-4 and y=-12
