To solve the expression \(-\frac{3}{10} - \frac{5}{12} - \frac{3}{10} - \frac{5}{12}\), we first combine the like terms.

1. Combine \(-\frac{3}{10}\) terms:
\[
-\frac{3}{10} - \frac{3}{10} = -\frac{6}{10}
\]

2. Combine \(-\frac{5}{12}\) terms:
\[
-\frac{5}{12} - \frac{5}{12} = -\frac{10}{12}
\]

Now, we can express the entire equation as:
\[
-\frac{6}{10} - \frac{10}{12}
\]

Next, we need a common denominator to combine these fractions. The least common multiple of \(10\) and \(12\) is \(60\).

3. Convert each fraction to have a denominator of \(60\):
\[
-\frac{6}{10} = -\frac{6 \times 6}{10 \times 6} = -\frac{36}{60}
\]
\[
-\frac{10}{12} = -\frac{10 \times 5}{12 \times 5} = -\frac{50}{60}
\]

4. Now combine the fractions:
\[
-\frac{36}{60} - \frac{50}{60} = -\frac{36 + 50}{60} = -\frac{86}{60}
\]

5. Simplify if possible:
\[
-\frac{86}{60} = -\frac{43}{30} \quad \text{(dividing both numerator and denominator by 2)}
\]

Thus, the final result is:
\[
-\frac{43}{30}
\]

If we assume \(bnh\) represents this value, then:
\[
bnh = -\frac{43}{30}
\]