The answer is x = 12.
Here are the steps I used.
1. Simplify 1 - 1 + 20x - 4300 to 20x - 4300 ( 20x - 4300 = -4060)
2. Add 4300 to both sides ( 20x = -4060 + 4300)
3. Simplify -4060 + 4300 to 240 ( 20x = 240)
4. Divide both sides by 20 ( x = 240/20)
5. Simplify 240/20 to 12 ( x = 12)