(80)/ ? = ? /(20)

Options

A. 40
B. 400
C. 800
D. 1600

Answer

To solve the equation \( \frac{80}{?} = \frac{?}{20} \), we can follow these steps:

### Step 1: Set up the equation
Let the question mark be represented by \( x \). Therefore, we can rewrite the equation as:
\[ \frac{80}{x} = \frac{x}{20} \]

### Step 2: Cross-multiply
To eliminate the fractions, we can cross-multiply:
\[ 80 \cdot 20 = x \cdot x \]
This simplifies to:
\[ 1600 = x^2 \]

### Step 3: Solve for \( x \)
To find \( x \), we take the square root of both sides:
\[ x = \sqrt{1600} \]

### Step 4: Calculate the square root
Calculating the square root gives us:
\[ x = 40 \]

### Step 5: Conclusion
Thus, the value of the question mark is:
\[ \text{Question mark} = 40 \]