Let's evaluate each expression step by step:

1. First expression: $-5 \times (-2.4)$ Multiplying two negative numbers results in a positive number: $-5 \times (-2.4) = 12$

2. Second expression: $-7.4 \div 10$ Dividing a negative number by a positive number results in a negative number: $-7.4 \div 10 = -0.74$

3. Third expression: $\frac{-4}{7} \div (-2)$ Dividing two negative numbers results in a positive result. First, rewrite the division as multiplication by the reciprocal: $\frac{-4}{7} \times \frac{-1}{2} = \frac{4}{14} = \frac{2}{7}$

4. Fourth expression: $4 \times \left(-\frac{3}{8}\right)$ Multiplying a positive number by a negative fraction results in a negative value: $4 \times \left(-\frac{3}{8}\right) = -\frac{12}{8} = -1.5$

The final results for each expression are:

1. $12$
2. $-0.74$
3. $\frac{2}{7}$
4. $-1.5$

Would you like any more details on these steps, or do you have any questions?

Here are 5 related questions:

1. What happens when you multiply a positive number by a negative number?
2. How do you divide fractions, and why is the reciprocal used?
3. What is the result of dividing a number by 10?
4. Why does the product of two negative numbers result in a positive number?
5. Can you convert a decimal into a fraction?

Tip: When dividing fractions, always remember to multiply by the reciprocal of the divisor.