请教Prep 2-41 （已经解决）

Last Thursday, John assembled chairs at a rate of 3 chairs per hour for part of the day and Larry assembled no chairs.  Last Friday, Larry assembled chairs at a rate of 4 chairs per hour for part of the day and John assembled no chairs.  If John and Larry assembled chairs for a total of 7 hours during these two days, how many chairs did John assemble last Thursday?

(1)  During these two days, John and Larry assembled a total of 25 chairs.

(2)  During these two days, Larry assembled more chairs than John did.

答案好像是A,但是我怎么觉得是C呢？

根据（1）， 3J+4L=25, 当J=7, L=1; 当J=3, L=4;所以不充分

根据(2),也不充分

两个加起来，充分，因为4L>3J,所以 满足条件的只有J=3,L=4.

是我看到的版本答案错了么？ 请NN赐教！

哦，少看了一个条件， J+L=7...真粗心啊。。。