Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

If x is a non-zero integer (40 + 24)/x is an integer?

(1) x is a multiple of 4

(2) 8 <= x <= 64

If we modify the question, we ultimately want to know whether x is a factor of 64. There is one variable (x) and we need one equation to solve for the question; there are 2 equations given from the 2 conditions, making (D) our likely answer.

In condition 1, the answer is 'yes' when x=4, but 'no' when it is 12. This condition is insufficient.

In condition 2, the answer is 'yes' when x=4, but 'no' when it is 12. This condition is insufficient.

When looking at the conditions together, the answer is 'yes' when x=4, but 'no' when it is 12. This conditions as a whole are insufficient.

For cases where we need 1 more equation, such as original conditions with “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 59 % chance that D is the answer, while A or B has 38% chance and C or E has 3% chance. Since D is most likely to be the answer using 1) and 2) separately according to DS definition. Obviously there may be cases where the answer is A, B, C or E.

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