A number, when decreased by `20%` becomes 136. What is the number ?

Options

A. 160
B. 150
C. 170
D. 140

Explanation

To find the original number that, when decreased by 20%, becomes 136, we can follow these steps:

### Step 1: Define the original number
Let the original number be \( X \).

### Step 2: Express the decrease
When the number \( X \) is decreased by 20%, it means we are left with 80% of \( X \). This can be expressed mathematically as:
\[ X - 0.20X = 0.80X \]

### Step 3: Set up the equation
According to the problem, when \( X \) is decreased by 20%, it equals 136. Therefore, we can write the equation:
\[ 0.80X = 136 \]

### Step 4: Solve for \( X \)
To find \( X \), we can divide both sides of the equation by 0.80:
\[ X = \frac{136}{0.80} \]

### Step 5: Calculate \( X \)
Now, we can perform the division:
\[ X = \frac{136}{0.80} = \frac{136 \times 100}{80} = \frac{13600}{80} = 170 \]

### Conclusion
Thus, the original number is:
\[ \boxed{170} \]

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