Bunuel wrote:

Is quadrilateral ABCD a square?

(1) AB = BC = CD = DA

(2) x + y = 180

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Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

A quadrilateral has 5 variables by VA method.

Since we have 3 equations from the condition 1) and we have 1 equation from the condition 2), both conditions together are not sufficient.

E is the answer.

For cases where we need 3 more equations, such as original conditions with “3 variables”, or “4 variables and 1 equation”, or “5 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 80 % chance that E is the answer, while C has 15% chance and A, B or D has 5% chance. Since E is most likely to be the answer using 1) and 2) together according to DS definition. Obviously there may be cases where the answer is A, B, C or D.

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