Simplify these fractions: 1. (18)/(8) x (15)/(3) x (16)/(4) 2. (12)/(4) x (16)/(12) x (y)/(8)

$$\frac{18}{8} \times \frac{15}{3} \times \frac{16}{4}$$

Cancel 15 and 3: $15 \div 3 = 5$, $3 \div 3 = 1$.
Cancel 16 and 4: $16 \div 4 = 4$, $4 \div 4 = 1$.
The expression becomes:

$$\frac{18}{8} \times \frac{5}{1} \times \frac{4}{1}$$

Cancel 18 and 8 by dividing by 2: $18 \div 2 = 9$, $8 \div 2 = 4$.
The expression becomes:

$$\frac{9}{4} \times \frac{5}{1} \times \frac{4}{1}$$

Cancel 4 (denominator of the first fraction) and 4 (numerator of the third fraction): $4 \div 4 = 1$.
The expression becomes:

$$\frac{9}{1} \times \frac{5}{1} \times \frac{1}{1}$$

$$\frac{9 \times 5 \times 1}{1 \times 1 \times 1} = \frac{45}{1} = 45$$

The final answer is $\boxed{\text{45}}$.

: $\frac{12}{4} \times \frac{16}{12} \times \frac{y}{8}$

$$\frac{12}{4} \times \frac{16}{12} \times \frac{y}{8}$$

Cancel 12 (numerator of the first fraction) and 12 (denominator of the second fraction): $12 \div 12 = 1$.
The expression becomes:

$$\frac{1}{4} \times \frac{16}{1} \times \frac{y}{8}$$

Cancel 16 (numerator of the second fraction) and 4 (denominator of the first fraction): $16 \div 4 = 4$, $4 \div 4 = 1$.
The expression becomes:

$$\frac{1}{1} \times \frac{4}{1} \times \frac{y}{8}$$

Cancel 4 (numerator of the second fraction) and 8 (denominator of the third fraction): $4 \div 4 = 1$, $8 \div 4 = 2$.
The expression becomes:

$$\frac{1}{1} \times \frac{1}{1} \times \frac{y}{2}$$

$$\frac{1 \times 1 \times y}{1 \times 1 \times 2} = \frac{y}{2}$$

The final answer is $\boxed{\frac{y}{2}}$.

: $\frac{18}{9} \times \frac{16}{9} \times \frac{12}{4}$

$$\frac{18}{9} \times \frac{16}{9} \times \frac{12}{4}$$

Cancel 18 and 9: $18 \div 9 = 2$, $9 \div 9 = 1$.
The expression becomes:

$$\frac{2}{1} \times \frac{16}{9} \times \frac{12}{4}$$

Cancel 12 and 4: $12 \div 4 = 3$, $4 \div 4 = 1$.
The expression becomes:

$$\frac{2}{1} \times \frac{16}{9} \times \frac{3}{1}$$

Cancel 3 (numerator of the third fraction) and 9 (denominator of the second fraction): $3 \div 3 = 1$, $9 \div 3 = 3$.
The expression becomes:

$$\frac{2}{1} \times \frac{16}{3} \times \frac{1}{1}$$

$$\frac{2 \times 16 \times 1}{1 \times 3 \times 1} = \frac{32}{3}$$

The final answer is $\boxed{\frac{32}{3}}$.