Frank cuts x even columns and 3 even rows into the pan of brownies, which means there are x * 3 = 3x brownies in total.
There are 6 people in total, including Frank, so they can each eat 3x / 6 = 0.5x brownies.
We are given that they can each eat 3 brownies, so we can write: 0.5x = 3.
Solving for x, we get: x = 6.
The value of x is 6.
#### 6
The answer is: 6
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
Frank invites his friends over to play video games. He bakes a pan of brownies before he arrives. He cuts x even columns and 3 even rows into the pan of brownies. If there are 6 people, including Frank, in total, how many brownies can they each eat?
If we know the answer to the above question is 3, what is the value of unknown variable x?

### Answer:
