If k is a positive two-digit integer, what is the tens

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If k is a positive two-digit integer, what is the tens digit of k?

1) The sum of the tens digit of k and the units digit of k is 5.

2) The tens digit of k + 6 is 3.

The OA is the option C.

How can I solve this DS question? I don't know what to do. Help, please.

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by GMATGuruNY » Fri Apr 20, 2018 4:42 am

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M7MBA wrote:If k is a positive two-digit integer, what is the tens digit of k?

1) The sum of the tens digit of k and the units digit of k is 5.

2) The tens digit of k + 6 is 3.
Statement 1:
Case 1: k=14, with the result that the tens digit of k is 1
Case 2: k=23, with the result that the tens digit of k is 2
Since the tens digit can be different values, INSUFFICIENT.

Statement 2:
Make a list of option for k+6:
k+6 = 30, 31, 32, 33, 34, 35, 36, 37, 38, 39.
To yield options for k, subtract 6 from every value in the list above:
k = 24, 25, 26, 27, 28, 29, 30, 31, 32, 33.
Since the tens digit of k can be 2 or 3, INSUFFICIENT.

Statements combined:
In the blue list above, only k=32 is such that the sum of the digits is 5.
Thus, k=32, with the result that the tens digit of k is 3.
SUFFICIENT.

The correct answer is C.
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