To solve this problem, we need to determine the value of x, which represents the total number of students at the school.
We know that 40% of the students receive a free lunch, which means 60% of the students pay for their lunch.
Let's set up the equation as follows:
Total cost of feeding x students = Cost per paying student * Number of paying students
$210 = $7 * (0.6x)
Let's simplify and solve for x:
$210 = $4.2x
To isolate x, we divide both sides of the equation by $4.2:
$210 / $4.2 = $4.2x / $4.2
50 = x
The value of x is 50.
#### 50
The answer is: 50
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
At a school, 40% of the students receive a free lunch. These lunches are paid for by making sure the price paid by the paying students is enough to cover everyone's meal. If it costs $210 to feed x students, The paying students pay 7 for lunch. What is the value of unknown variable x?

### Answer:
