tarek99 wrote:
If the units digit of the three-digit positive integer k is nonzero, 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.
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I put three imaginary numbers down on the page _x_ _y_ _z>1_ , where the tens digit is greater than 1.
(AD BCE)
1) If tens digit is 3, then I tried with lowest possible number that conformed: t=121. 121+9=130, and also highest, where t-129: 129+9=138
therefore tens unit is 3, thus sufficient.
(Cross out BCE --> AD left)
2) Again tried the extreme cases:121 and 129. Tens digit could either be 2 (121+4=125) or 3 (129+4=133). Therefore, Not sufficient.
Therefore A is sufficient.
Is this logic ok? Thanks