A plane ticket has gone up 18%, now costing $4,720. How much did it cost before the increase?

\text{Solution:}
1. Define variables:
- Let P be the original price of the plane ticket.
- P increased by 18% means the new price is P + 0.18P = 1.18P.

2. Set up the equation based on the problem statement:
- The new price = 4,720.
- Therefore, 1.18P = 4,720.

3. Solve for P:
- Divide both sides by 1.18 to isolate P.
P = \frac{4,720}{1.18}.

4. Calculate:
- P \approx 4,000.

\text{Answer:}
- The original price of the plane ticket was approximately USD 4,000.