bubbliiiiiiii wrote:

500 is the multiple of 100 that is closest to x
In other words, of the values 100, 200, 300, 400, 500, 600, (etc), the multiple that is closest to x is 500
This means that: 450 < x < 550 (e.g., if x were greater than 550 it would be closer to 600, not 500)

Similarly, if 400 is the multiple of 100 that is closest to y then: 350 < y < 450

We want to find the multiple of 100 that is closest to x+y

Statement 1: x < 500
Since we already know that 450 < x < 550, statement 1 tells us that 450 < x < 500
So, if 450 < x < 500 and if 350 < y < 450, we can add the inequalities to get: 800 < x+y < 950
From this, we can see that x+y could be closer to 800 or it could be closer to 900
INSUFFICIENT

Statement 2: y < 400
From this, we can use the same logic to see that 350 < y < 400
Since we already know that 450 < x < 550, we can add the inequalities to get: 800 < x+y < 950
From this, we can see that x+y could be closer to 800 or it could be closer to 900
INSUFFICIENT

Statements combined 2:
(1) tells us that 450 < x < 500
(2) tells us that 350 < y < 400
When we combine these, we see that 800 < x+y < 900

Since the sum of x+y could be closer to 800 or it could be closer to 900, the statements combined are INSUFFICIENT so the answer is E