To solve the problem, let's break down the calculation step by step:
1. **Calculate the sum of the first two numbers:**
\[
3 + 5 = 8
\]
2. **Calculate the sum of the next two numbers:**
\[
4 + 2 = 6
\]
3. **Calculate the sum of the last two numbers:**
\[
10 + 8 = 18
\]
4. **Calculate the sum of the first and second sums:**
\[
8 + 6 = 14
\]
5. **Subtract the sum of the third and fourth numbers from the result of step 4:**
\[
14 - (15 - 5) = 14 - 10 = 4
\]
Therefore, the final result of the calculation is \( \boxed{4} \).
