Hi All,
This question has a number of built-in patterns that you can take advantage of. First, the answer choices are small integers, so you can TEST THE ANSWERS. Second, the numbers involved are also all integers... Maura bought $12 worth of mangoes at a merchant, but the mangos are $1 cheaper per pound at the shopping center - and at that price she could purchase 1 extra pound of mangos for $12..
From the answer choices, we can see that the total cost per pound at the merchant must ALSO be an integer... almost certainly one that divides evenly into $12. So we need two integers, one for each of the two prices... that BOTH divide into $12 AND that differ by $1. That can ONLY be $3 and $4. Now we just have to double-check to make sure that we're answering the question that is asked...
$12 spent at the merchant (where mangoes are $4 a pound) = 3 pounds
$12 spent at the center (where mangoes are $3 a pound) = 4 pounds
This matches perfectly. The question asks for the price per pound at the merchant....
Final Answer:
GMAT assassins aren't born, they're made,
Rich