求解The annual rent

ozymendias

The annual rent collected by a corporation from a certain building was x percent more in 1998 than in 1997 and y percent less in 1999 than in 1998. Was the annual rent collected by the corporation from the building more in 1999 than in 1997?
(1) x > y
(2) xy/100 < x - y

答案是B，求解。谢谢

linmeimei

列式子，用1999年/1997年>1

haileywang

设1997 年Rent 为a;
1998 年Rent 为 (1+x/100)a;
1999 年Rent 为 (1+x/100)(1-y/100)a;

分解(1+x/100)(1-y/100)a = (1-y/100+x/100-xy/10000)a
算出1-y/100+x/100-xy/10000是否大于1，即可知道问题的答案。
根据条件二，可知大于1