Hi VJesus12,
We're told that a mobile app store sells all of its mobile apps at one FIXED price and all of its mobile books for another FIXED price, and that David, Patrick and Emily purchased digital products from this mobile app store. We're asked for the total that Patrick paid for 1 mobile app and 1 mobile book.
1) David paid $15 for 2 mobile apps and 3 mobile books.
With this information, we can create the following equation:
2A + 3B = 15
Unfortunately, this is just one equation and two variables - and it has multiple solutions:
For example...
IF A=3 and B=3, then the answer to the question is 1(3) + 1(3) = 6
IF A=6 and B=1, then the answer to the question is 1(6) + 1(1) = 7
Fact 1 is INSUFFICIENT.
2) Emily paid $30 for 4 mobile apps and 6 mobile books.
With this information, we can create the following equation:
4A + 6B = 30
You should notice that each term is EXACTLY DOUBLE the respective term in the equation from Fact 1 - meaning that this is NOT a 'new' equation; it's the same equation as before). Just as in Fact 1, this is just one equation and two variables - and it has multiple solutions (and it will have the exact same possible solutions as the equation in Fact 1):
For example...
IF A=3 and B=3, then the answer to the question is 1(3) + 1(3) = 6
IF A=6 and B=1, then the answer to the question is 1(6) + 1(1) = 7
Fact 2 is INSUFFICIENT.
Combined, we know that we're really given just 1 unique equation, but even if you didn't recognize that, you can see that the same examples 'fit' BOTH Facts, so there are multiple answers to the given question.
Combined, INSUFFICIENT
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
