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 the two horizontal lines in the figure provided are parallel, what is (a + f + d) – (e + h)?
(1) a + f = 180
(2) a – f = 60
Transforming the original condition and the question, we have a=d=e=h thus (a + f + d) – (e + h)?--> f=?. a+f=180 we have 2 variables (a,f), and 1 equation (a+f=180) therefore we need 1 more equation. Therefore there is high probability that D is the answer
In case of 1), a+f=180 is the repetition of the original condition. Therefore the condition is not sufficient.
In case of 2), a-f=60 and a+f=180 gives us 2f=120, f=60. Therefore the condition is sufficient, and the answer is B.
Attachments

Picture-3.png [ 10.38 KiB | Viewed 4334 times ]