Billy can spit a watermelon seed x inches.
Madison can spit a watermelon seed 20% farther than Billy, which means Madison can spit a seed (1 + 0.20)x inches.
Ryan can spit a watermelon seed 50% shorter than Madison, which means Ryan can spit a seed (1 - 0.50)(1 + 0.20)x inches.
Simplifying, we get Ryan can spit a seed (0.50)(1.20)x inches.
We are given that Ryan can spit a seed 18 inches, so we can write: (0.50)(1.20)x = 18.
Simplifying, we get: (0.60)x = 18.
Dividing both sides by 0.60, we get: x = 30.
The value of x is 30.
#### 30
The answer is: 30
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
Billy can spit a watermelon seed x inches.  Madison can spit a watermelon seed 20% farther than Billy.  Ryan can spit a watermelon seed 50% shorter than Madison.  How far can Ryan spit a watermelon seed?
If we know the answer to the above question is 18, what is the value of unknown variable x?

### Answer:
