I just began studying GMAT last week and borrowed a used Princeton Review: Cracking the GMAT 2009 Edition. On page 85, there is a DS question that reads:
If ax + ay = 15, what is x + y + z?
(1) x = 2
(2) a = 5
The answer in the back reads: Statement (1) gives us a value ofr x, but we need x + y + z. Statement (1) is not sufficient. We're down to BCE. Statement (2) might not have seemed much more helpful, BUT using the distributive property, we can rewrite the orginal equation to read a(x+y+z) = 15. If a is 5, then x + y + z must equal 3. The correct answer is choice B.
I don't understand how the explanation states to write the equation as a(x+y+z) when the orignal problem only has ax + ay = 15. Is there a typo? Or am I just missing something here?
If ax + ay = 15, what is x + y + z?
(1) x = 2
(2) a = 5
The answer in the back reads: Statement (1) gives us a value ofr x, but we need x + y + z. Statement (1) is not sufficient. We're down to BCE. Statement (2) might not have seemed much more helpful, BUT using the distributive property, we can rewrite the orginal equation to read a(x+y+z) = 15. If a is 5, then x + y + z must equal 3. The correct answer is choice B.
I don't understand how the explanation states to write the equation as a(x+y+z) when the orignal problem only has ax + ay = 15. Is there a typo? Or am I just missing something here?
