`250 mL` of nitrogen gas maintained at `720 mm` pressure and `380 mL` of oxygen gas maintained at `650 mm` pressure are put together in `1 L` flask. If temperature is kept constant, what will be the final pressure of the mixture?

Explanation

To solve the problem, we will use the principles of gas laws, specifically Boyle's Law, and Dalton's Law of Partial Pressures.

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Volume of nitrogen gas (V₁) = 250 mL
- Pressure of nitrogen gas (P₁) = 720 mmHg
- Volume of oxygen gas (V₂) = 380 mL
...