{Y= 3x

Question

Y-x=4

So far I have done this. Please tell me the next steps. Thank you.

X=Y-4

Y=3(4-Y)
Y=12-3Y

Answer 1

from
x = y-4 , sub in y=3x
x = 3x - 4
x - 3x= -4
-2x = -4
divide both sides by -2
x = 2

sub into y=3x
y = 3(2) = 6

x = 2, y = 6

your second last line
Y=3(4-Y)
should have said:
Y = 3(y-4)

then
y = 3y - 12
-2y = -12
y = 6, just like I had mine

Answer 2

y = 3 x

y - x = 4

3 x - x = 4

2x = 4 Divide both sides by 2

x = 4 / 2 = 2

y = 3 x

y = 3 * 2 = 6