If y = 4x then you'd input that information into your equation making: 3x-4x = 1
The correct solution is: 3(-1)-4(-1) = 1

Llama11

y = 4x .....(a)
3x - y = 1. ......(b)
Substitute y = 4x in (a) into (b)
3x - y = 1......(b)
3x - 4x = 1
-x = 1
x = -1
Recall, y = 4x ........(a)
y = 4*(-1)
y = -4.
Therefore, x = -1, and y = -4.