a math answer

rocker

1. K is a three digit integer, whose unit digit is not zero. What is the tens digit of K.
(1) The tens digit of K + 9 is 3
(2) The tens digit of K + 4 is 2

The answer should be  E.

from (1): if K is positive   ==> tens digit: 2
               if K is Negative ==>tens digit: 3 or 4
from (2): if K is positive   ==>tens digit: 1 or 2
               if K is nagative ==> tens digit: 2 or 3

from both (1) and (2), tens digit could be 2 or 3.

tongxun

I agree with you。 when I did this question， I forgot the condition of negative，and now must recheck my answer。