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.
All of the tickets for 2 music concerts, X and Y, were either purchased or given away, and the ratio of X tickets to Y was 2 to 1. Of the total number of X tickets and Y tickets, what percentage was purchased?
(1) The total number of X tickets and Y tickets, is 240.
(2) Of the X tickets, exactly 60% were purchased, and of the Y tickets, exactly 80% were purchased.
In a 2 by 2 question as above, if a condition has 3 values of percentages when the question is asking for percentages, the condition becomes sufficient.
Attachment:
GC DS Bunuel All of the tickets for (20151104).jpg [ 29.84 KiB | Viewed 7734 times ]
There are 2 variables (x,y) and 2 equations regarding percentages are given from the 2 conditions, (especially condition 2 has 2 values of percentages), so the condition is sufficient.
x=36, y=24. The answer becomes (B).
from con 1) and con 2), if one of the conditions is given by numbers and the other is given by ratio (percent,fraction), then the condition with ratio (percent,fraction) value has higher chance of being the answer.