How many sweaters does Jim own?
(1) Jim owns 12 wool sweaters.
(2) 60 percent of the sweaters Jim owns are not wool.";



The question asks \"How many sweaters does Jim own\" and not \"How many woolen sweaters does Jim own\". If the explained answer is to be right then i think the question should be modified to include the word woolen.

The answer is correct. You need both statements to correctly figure out how many sweaters Jim owns. 2 tells us that 40% of his sweaters are wool. And so 0.4x = 12 (from (1)) allows us to solve for x, the number of sweaters Jim owns. We don't actually have to solve for x since it is data sufficiency.