Statement 1:
x - y is positive means x - y > 0
Or, x > y ....... Rewriting it this way makes it much easier to think about the situation in my opinion
Knowing that x > y definitely does not allow us to determine if their sum is positive.
You could plug in numbers to show this, but I think it's useful to try thinking through this at this slightly higher level.
Statement 2:
x/y is positive
For the product of two numbers to be positive, the two must have the same sign. They both could be positive (in which case the sum is positive). They both could be negative (in which case the sum is negative).
Again, You could plug in numbers to show this, but here as well I think it's useful to try thinking through this at this slightly higher level.
Combined:
[spoiler]The two numbers must have the same sign. And one of them (x) has to be bigger than the other one(y). It's still true that they both could be positive (in which case the sum is positive), or that they both could be negative (in which case the sum is negative).[/spoiler]
Numbers
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GMAT Boost offers 250+ challenging GMAT Math practice questions, each with a thorough video explanation, and 100+ GMAT Math video tips, each 90 seconds or less.
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Also, check out the most useful GMAT Math blog on the internet here.
