Answer: First option
Step-by-step explanation:
You have the quadratic equation given in the problem:

To find an equivalent expression you cacn factorize. Find two numbers whose sum is -13 and whose product is -30.
These numbers would be -15 and 2.
Therfore, you obtain the following equivalent expression:

If you don't want to apply the method above, you can use the quadratic formula:

Where:

When you susbstitute values you obtain that:

Then you can rewrite the equation as 
In this question there are several information's of immense importance already given.
The number of pair of gloves that the merchant bought = 30 dozens
1 dozen = 12 gloves
Also
1 pair = 2 gloves
Then
The total numberof individual gloves bought
by the merchant = 30 * 12 * 2
= 720
The correct option among all the options given in the question is option "C" and it can be checked via the above solution.
*You could use a calculator
50 times 50 times 50 times 20 equals <span>2500000</span>
Your answer is <em>2500000</em>