[email protected] wrote:I find this confusing why is it structured this way? And under which category of questions does this come?

Dear shibsriz,
I'm happy to respond.

This question is about something in math known as a piecewise function. These are studied in advanced Precalculus and Calculus classes. I would say it's a little beyond anything the GMAT would give, except as a really advanced 800+ level problem.

Uva@90 gave a good response. Statement #1 is definitely not sufficient by itself.

For statement #2, if the shipping costs for the two orders are d = 3 and d = 7, the latter would have a price over $500. Suppose the two shipping costs are d = 5 and d = 5. What is the price of the merchandise, x, when d = 5?

d = 5 = 3 + (x - 100)/100
Multiply by 100
500 = 300 + (x - 100)
200 = x - 100
300 = x

So, if each order has a shipping cost of d = 5, then each order has a merchandise cost of x = $300, and the combined cost is $600. Because the function is a linear function, it turns out that if we increase one d above 5, and reduce the other d below 5 by the same amount, the sum of the merchandise costs will remain $600. To see that requires tremendous intuition about the nature of functions. Once again, we are in territory here well beyond what the GMAT typically tests.

Here's a blog you may find helpful:
https://magoosh.com/gmat/2013/mathematic ... -the-gmat/

Let me know if you have any further questions.
Mike