Evaluate the numerator.

Step 1: Evaluate the numerator.

$$2.4 \times 1.68 \times 0.3 = 4.032 \times 0.3 = 1.2096$$

Step 2: Evaluate the denominator.

$$0.32 \times 0.9 \times 6 = 0.288 \times 6 = 1.728$$

Step 3: Divide the numerator by the denominator.

$$\frac{1.2096}{1.728}$$

To simplify the division, multiply both numerator and denominator by 10000 to remove decimals:

$$\frac{12096}{17280}$$

Step 4: Simplify the fraction.

$$\frac{12096}{17280} = \frac{12096 \div 1728}{17280 \div 1728} = \frac{7}{10}$$

As a decimal:

$$\frac{7}{10} = 0.7$$

The final answer is $\boxed{0.7}$.

b) Evaluate $3\frac{1}{2} + (3\frac{1}{4} \text{ of } 2\frac{2}{3}) + 1\frac{1}{8}$

Step 1: Convert all mixed numbers to improper fractions.

$$3\frac{1}{2} = \frac{(3 \times 2) + 1}{2} = \frac{7}{2}$$ $$3\frac{1}{4} = \frac{(3 \times 4) + 1}{4} = \frac{13}{4}$$ $$2\frac{2}{3} = \frac{(2 \times 3) + 2}{3} = \frac{8}{3}$$ $$1\frac{1}{8} = \frac{(1 \times 8) + 1}{8} = \frac{9}{8}$$

Step 2: Solve the "of" part, which means multiplication.

$$3\frac{1}{4} \text{ of } 2\frac{2}{3} = \frac{13}{4} \times \frac{8}{3}$$ $$$$