请教prep数学题

lilychou0128

if 500 is the multiple of 100 that is close to x，and 400 is the multiple of 100 that is close to y，which is the multiple of 100 that is close to x+y？
1. x<500
2.y<400
这道题看不懂啊， 答案给的是E

sdcar2010

multiple of 100: 100, 200, 300, 400, 500, 600, . . .

Among the above candidates, 500 is the closest to x and 400 is the closest to y. Do you know which of the above numbers is closest to x+y?

Premise:  450<x<550 and 350<y<450

condition 1) 450<x<500, 800<x+y<950.  The multiple of 100 could be 800, 900,
condition 2) 350<y<400, 800<x+y<950.  The multiple of 100 could be 800, 900
conditions 1) and 2) 450<x<500, 350<y<400, 800<x+y<900. The multiple of 100 could be 800, 900.

EEEEEEEEEEEEEeee

lilychou0128

哦~原来是这个意思啊，谢谢哈~