lionsshare wrote:x-4=z
y-x=8
8-z=t

For the system of equations given, what is the value of z?

(1) x = 7
(2) t = 5

We are given 3 equations:

1) x - 4 = z
2) y - x = 8
3) 8 - z = t

We need to determine the value of z.

Statement One Alone:

x = 7

We see that we can substitute 7 for x in the first equation and then determine the value of z.

x - 4 = z
7 - 4 = z
3 = z

Statement one alone is sufficient to answer the question.

Statement Two Alone:
t = 5

We see that we can substitute 5 for t in equation 3 and then determine the value of z.
8 - z = t
8 - z = 5
3 = z

Statement two alone is sufficient to answer the question.

Answer: D