Solve the system x - y = 3 and 3x - 8y = 9. What is the value of y?

Question

anonymous · Answer

Answer choices available: 

	A.	3
	B.	0
	C.	6
	D.	-2

anonymous · Answer

From the first equation, we can rearrange to get x:

x - y = 3
x = y + 3

Plug this into the second equation and we get:
3(y + 3) + 8y = 9
3y + 9 + 8y = 9
11y = 0
y = 0

Then substitute y back in the original equation:
x - y = 3
x - 0 = 3
x = 3

A is your answer.

anonymous · Answer

Thank you SirSushii! :)

mathmate · Answer

What is the value of y?
3 times the first equation subtract the second gives
3x - 3y = 9 and
3x - 8y = 9
Subtracting,
5y=0 => y=0
B is the answer for y.

anonymous · Answer

Oops. My bad. xD

mathmate · Answer

:)

anonymous · Answer

Oh dang! Well, it is the thought that counts! :) Thanks mathmate, and I still thank you SirSushii for trying to help me! Thanks both of you! :)

mathmate · Answer

You're welcome!  :)