Find: b. `(15)/(16) xx (4)/(21)`

Answer

To solve the problem \( \frac{15}{16} \times \frac{4}{21} \), we will follow these steps:

### Step 1: Write the fractions
We start with the fractions:
\[ \frac{15}{16} \times \frac{4}{21} \]

### Step 2: Multiply the numerators
Next, we multiply the numerators (the top parts of the fractions):
\[ 15 \times 4 = 60 \]

### Step 3: Multiply the denominators
Now, we multiply the denominators (the bottom parts of the fractions):
\[ 16 \times 21 = 336 \]

### Step 4: Write the result as a single fraction
Now we can write the result as a single fraction:
\[ \frac{60}{336} \]

### Step 5: Simplify the fraction
To simplify \( \frac{60}{336} \), we need to find the greatest common divisor (GCD) of 60 and 336.

- The prime factorization of 60 is \( 2^2 \times 3 \times 5 \).
- The prime factorization of 336 is \( 2^4 \times 3 \times 7 \).

The GCD is \( 2^2 \times 3 = 12 \).

Now, we divide both the numerator and the denominator by 12:
\[ \frac{60 \div 12}{336 \div 12} = \frac{5}{28} \]

### Final Answer
Thus, the simplified result of \( \frac{15}{16} \times \frac{4}{21} \) is:
\[ \frac{5}{28} \]

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