请大牛看看：Was Lisa’s annual salary at least twice as much as Julie’s annual salary?

yunduanxw

Was Lisa’s annual salary at least twice as much as Julie’s annual salary?
(1) Lisa’s annual salary was $20,000 more than Julie’s annual salary.
(2) Lisa’s annual salary was less than $40,000.

Question: L >= 2J
Statement 1 : L = 20000 + J
Statement 2 : L < 40000
=> 20000+J<40000 => J<20000 => J + J < 20000 + J => L > 2J
无法推出L >= 2J
所有的答案都说是C，我哪里有错吗？

NBibi

用特殊数是可以的~
只需A：把符合B的和不符合B的都试一次，50000<30000*2, 30000>10000*2，不行
只需B：不知J的salary，不行
A+B：30000>10000*2
         或39000>19000*2

NBibi

只要L>2J，L一定会>=2J……
lz明白没~
小范围一定可以得出大范围的