To solve the division of fractions, multiply the first fraction by the reciprocal of the second fraction.
Step 1: Define the Fractions
We start with the expression \( -\frac{3}{2} \div \left(\frac{9}{10}\right) \). This can be rewritten as:
\[
-\frac{3}{2} \div \frac{9}{10}
\]
Step 2: Multiply by the Reciprocal
To divide by a fraction, we multiply by its reciprocal:
\[
-\frac{3}{2} \times \frac{10}{9}
\]
Step 3: Perform the Multiplication
Now, we multiply the numerators and the denominators:
\[
\frac{-3 \times 10}{2 \times 9} = \frac{-30}{18}
\]
Step 4: Simplify the Fraction
Next, we simplify \( \frac{-30}{18} \) by dividing both the numerator and the denominator by their greatest common divisor, which is 6:
\[
\frac{-30 \div 6}{18 \div 6} = \frac{-5}{3}
\]
Final Answer
Thus, the final result of the expression is:
\[
\boxed{-\frac{5}{3}}
\]