We have a solution called 'P'. Over two hours, some of this solution evaporates:
1. First hour: $8 \%$ of the initial solution 'P' evaporates.
2. Second hour: 5\% of the remaining solution after the first hour evaporates.

We need to find out what percentage of the initial solution ' $P$ ' is left after these two hours of evaporation.

Step 1: Initial Setup
Let's assume the initial amount of solution 'P' is 100 units for simplicity (since we're dealing with percentages, this makes calculations straightforward).
- Initial amount of 'P': 100 units

Step 2: First Hour Evaporation
In the first hour, 8\% of the initial solution evaporates.
- Amount evaporated in 1st hour: $8 \%$ of $\(100=0.08 \times 100=8\)$ units
- Remaining after 1st hour: 100-8 = 92 units

Step 3: Second Hour Evaporation
In the second hour, 5\% of the remaining solution evaporates. The remaining solution after the first hour is 92 units.
- Amount evaporated in 2nd hour: $5 \%$ of $\(92=0.05 \times 92=4.6\)$ units
- Remaining after 2nd hour: \(92-4.6 = 87.4\) units

Step 4: Calculating the Percentage Left
Now, we have 87.4 units left out of the original 100 units.
- Percentage left: $(87.4 / 100) \times 100=87.4 \%$

Verification
Let me verify the calculations to ensure no mistakes were made.
1. First hour:
- $8 \%$ of $100=8$
- 100-8 = 92 (correct)
2. Second hour:
- $5 \%$ of $\(92=0.05 \times 92=4.6\)$
- $\(92-4.6=87.4\)$ (correct)
3. Percentage left:
- 87.4 out of 100 is indeed $87.4 \%$

Alternative Approach: Using Multipliers
Another way to approach this is by using multipliers for the remaining percentages:
1. First hour: $8 \%$ evaporates, so $92 \%$ remains.
- Remaining $\(=100 \times 0.92=92\)$
2. Second hour: 5\% of the remaining evaporates, so 95\% of the remaining stays.
- Remaining $\(=92 \times 0.95=87.4\)$

Final Answer
After carefully calculating:
- After the first hour: $92 \%$ remains.
- After the second hour: $87.4 \%$ remains.

Therefore, $87.4 \%$ of the initial solution 'P' is left after 2 hours.