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.

In the figure above, all angles are right angles. If the lengths a, b, u, and v are integers, what is the perimeter of the six-sided figure?

(1) ab = 77

(2) u/v = 3/5

When you modify the original condition and the question, the length of the perimeter is 2(a+b). That is, you only need to figure out a+b. a and b are integers and (a,b)=(7,11),(11,7) from 1) ab=77. Also, a+b=18 is always derived and sufficient, which makes A the answer.

The reason (a,b)=(1,77) is not valid is if a=1, you cannot subtract u, which makes 1 impossible.

Thus, A is the answer.

Once we modify the original condition and the question according to the variable approach method 1, we can solve approximately 30% of DS questions.

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