I'm happy to give my 2¢ on this.

Prompt:
At a certain company, some of the 110 employees are part-time, and the rest are full-time. If 15 employees have an MBA, what percentage of the company's employees are male and hold an MBA?

In order to figure this out, we need to know how many of those 15 MBA holders are male. We already know the total number of employees, 110.

Statement #1: All 4 part-time employees who hold an MBA are female.
Seemingly irrelevant information --- we know about some of the female MBA folks, but not all of them, so from this alone, we cannot calculate how many MBA folks are male. Insufficient.

Statement #2: There are 6 female employees who hold an MBA and are not part-time. .
Very important to forget Statement #1 --- here, again, we know about some of the female MBA folks, but not all of them, so from this alone, we cannot calculate how many MBA folks are male. Insufficient.

Combined Statements #1 & #2:
All 4 part-time employees who hold an MBA are female
There are 6 female employees who hold an MBA and are not part-time.

Now, there's a possibility to combine information. There are 4 part-time female MBA holders and there are 6 full-time female MBA holders. Since full-time and part-time are the only two possibilities, there are a total of 10 females at the company with MBAs. If 10 of the 15 MBA holders are female, 5 are male.
Once we know the number of males with MBAs, we know we could calculate the percent. We don't even have to perform the percent calculation ---- on GMAT DS, it's enough to know: we know have enough information that we could calculate the answer if we wanted. Combined, the statements are sufficient.

Answer = C

As long as you are clear about what kinds of information you have and what kinds of information you need, you need now worry about Venn & charts and those things. Does this make sense?

Please let me know if you have any further questions.

Mike