Jane can fold 3 towels in 5 minutes, which means she can fold 3/5 towels per minute.
Kyla can fold 5 towels in 10 minutes, which means she can fold 5/10 towels per minute, or 1/2 towels per minute.
Anthony can fold x towels in 20 minutes, which means he can fold x/20 towels per minute.
If they all fold towels together, the total number of towels they can fold per minute is: 3/5 + 1/2 + x/20.
To find out how many towels they can fold in one hour (60 minutes), we can multiply the above expression by 60: 60 * (3/5 + 1/2 + x/20) = 36 + 30 + 3x.
We are given that they can fold 87 towels in one hour, so we can write: 36 + 30 + 3x = 87.
Simplifying the left side, we get: 66 + 3x = 87.
Subtracting 66 from both sides, we get: 3x = 21.
Dividing both sides by 3, we get: x = 7.
The value of x is 7.
#### 7
The answer is: 7
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
Jane, Kyla, and Anthony have summer jobs in a resort. Their task is to fold guests' towels. Jane can fold 3 towels in 5 minutes. Kyla can fold 5 towels in 10 minutes, and Anthony can fold x towels in 20 minutes. If they all fold towels together, how many towels can they fold in one hour?
If we know the answer to the above question is 87, what is the value of unknown variable x?

### Answer:
