其实我看不明白是什么意思

If 500 is the multiple of 100 that is closest to x and 400 is multiple of 100 that is closest to y, which multiple of 100 is cloest to x+y?

1) x<500

2) y<400

据个例子： x = 450,y=350-->x+y = 800; y = 450-->x+y = 900 (but x should be>=450, and y should be < 450, in that case it results in different outcome) similiar to (2)

if x= 450; y =399 => x+y <850 --> 800; x = 499, y =399=> x+y = 898-->900; yields diff outcome as well. So it should be E.

明白了,多谢!!!