The DS problem sets are interesting and it is obvious I need to change my mindset in order to solve them consistently.
Here is an example from the
MGMAT DS appendix:
If xyz ?= 0, is 3x/2 + y + 2z = 7x/2 + y?
(1) y=3 and x= 2
(2) z=-x
Without rewriting the question with like variables, you can use the info in statement 1 and find z=-2 pretty quickly BUT in the context of the question, that is still not sufficient.
That is going to take some undoing of old thought processes.
Immediately I jumped to the thought that "I now know z off of statement 1 alone and can solve" But in the context of the question statement 1 may give you z, which only then allows you to arrive at a "sufficient", but in itself finding z is not the same as making statement 1 sufficient on its own.
That's a convoluted way to tap that out on my phone, but hopefully that makes sense to my two readers and me when I look at this later.