`? - (8)/(21)=(8)/(21)`

Options

A. 0
B. 1
C. `(21)/(8)`
D. `(-8)/(21)`

Answer

To solve the equation \( ? - \frac{8}{21} = \frac{8}{21} \), we will follow these steps:

### Step 1: Rewrite the equation
Let’s represent the question mark with a variable. We can use \( x \) to represent it. So, we rewrite the equation as:
\[ x - \frac{8}{21} = \frac{8}{21} \]

### Step 2: Isolate the variable
To find the value of \( x \), we need to isolate it on one side of the equation. We can do this by adding \( \frac{8}{21} \) to both sides of the equation:
\[ x - \frac{8}{21} + \frac{8}{21} = \frac{8}{21} + \frac{8}{21} \]

### Step 3: Simplify both sides
On the left side, the \( -\frac{8}{21} \) and \( +\frac{8}{21} \) cancel each other out:
\[ x = \frac{8}{21} + \frac{8}{21} \]

### Step 4: Add the fractions
Now, we need to add the fractions on the right side. Since both fractions have the same denominator, we can simply add the numerators:
\[ x = \frac{8 + 8}{21} = \frac{16}{21} \]

### Step 5: State the final answer
Thus, the value of \( x \) (or the question mark) is:
\[ x = \frac{16}{21} \]