Ques. No. 20 in Algebra Question Bank (Expressing t and u)

[RahulS504]

The answer to this question is given as (A): Statement A ALONE is sufficient

But (A) and (B) together are also sufficient.

Question
(note that "-2" and "-3" are powers of t and u respectively. The exponents are not visible in the right format here in this post)

If t and u are positive integers, what is the value of t -2 u -3?

(1) t -3 u -2 = 1/36

(2) t( u -1) = 1/6

Solution:
If you multiply statement (1) and (2), you will get the value of t -2 u -3

[RonPurewal]

If one statement is already sufficient, you don't ever reach a point where you'd combine them.

[RahulS504]

Oh
I didn't know this. Thanks for the info
:)

[RonPurewal]

Oh
I didn't know this. Thanks for the info
:)

OK. Just make sure you understand the basics before you try "challenging" problems.

This is not some special weird GMAT thing, by the way——this is just the normal real-world use of evidence. If one piece of evidence is enough to establish something, then it would be silly to combine it with other evidence.
E.g., someone loses a bag. In the bag are (a) a bestselling book and (b) the person's passport.
Obviously (b) is good enough to tell me who the person is. There would be no reason to try to "combine" (a) and (b).

[RahulS504]

Sure.
But this problem was not as simple as the analogy driven above. The first choice in the analogy doesn't even link to the lost bag.
This problem was more like:
Someone loses a bag. In the bag are (a) a business card of the person (b) the person's passport.

But I get the concept of GMAT of stopping at the point where one is sufficient.

Thanks & Regards,
Rahul Singh

[RonPurewal]

Sure.
But this problem was not as simple as the analogy driven above. The first choice in the analogy doesn't even link to the lost bag.

Right.
That was the point. Lots and lots of people own that book (= the definition of "bestselling"), so that would be "not sufficient". There are many possibilities.

[RonPurewal]

This problem was more like:
Someone loses a bag. In the bag are (a) a business card of the person (b) the person's passport.

I didn't even look at the problem, since it was immaterial to your question. The first 2 lines of your post were sufficient for me to understand, and answer, your question. (:

Call it laziness; call it efficiency. Sometimes there's no difference.

But I get the concept of GMAT of stopping at the point where one is sufficient.

This is the only thing that matters. So, good.