What will be 80 percent of a number whose 200 percent is 90?

Options

A. 144
B. 72
C. 36
D. None of these

Answer

To solve the question "What will be 80 percent of a number whose 200 percent is 90?", we can follow these steps:

### Step 1: Define the variable
Let the unknown number be represented as \( X \).

### Step 2: Set up the equation for 200%
According to the problem, 200% of \( X \) is equal to 90. We can express this mathematically as:
\[ 200\% \text{ of } X = 90 \]
This can be rewritten as:
\[ \frac{200}{100} \times X = 90 \]

### Step 3: Simplify the equation
We can simplify \( \frac{200}{100} \) to 2:
\[ 2X = 90 \]

### Step 4: Solve for \( X \)
To find \( X \), divide both sides of the equation by 2:
\[ X = \frac{90}{2} = 45 \]

### Step 5: Find 80% of \( X \)
Now that we have \( X \), we need to find 80% of it:
\[ 80\% \text{ of } X = \frac{80}{100} \times 45 \]

### Step 6: Simplify the calculation
We can simplify \( \frac{80}{100} \) to \( 0.8 \):
\[ 0.8 \times 45 \]

### Step 7: Perform the multiplication
Calculating \( 0.8 \times 45 \):
\[ 0.8 \times 45 = 36 \]

### Conclusion
Thus, 80% of the number whose 200% is 90 is \( 36 \).