from GMAT Prep data sufficiency

Both statements are clearly insufficient on their own because the value of y is unkown.

Both statements together:

"4 is the integer that is closest to x+y"

basically, this means that x+y can be anywhere between 3.5 and 4.5. We can represent this as an inequality:

3.5 < x + y < 4.5

similary, for statement 2 we will arrive at:

0.5 < x - y < 1.5

adding both inequalities, we get:

3.5 + 0.5 < x + y + x - y < 4.5 + 1.5
4 < 2x < 6
2 < x < 3

From this inequality, we can see that it's still not sufficient to answer the question stem. If x=2.2, then the nearest integer will be 2, and if x=2.6, the nearest integer will be 3.

Choose E.

-BM-