Question

{(x,y): x-3y=4}
x-3y=4
Qx-6y=8

Find Q? It doesn't make sense to me.

Answer 1

You have to give Q such a value it makes the equations in the system become equal

x - 3y = 4 -> 2x - 6y = 8
|
Qx - 6y = 8
Q = 2


We could similarly do

Qx - 6y = 8 -> Q/2 x - 3y = 4
|
1 x - 3y = 4

Q/2 = 1 <=> Q = 2