65% of `654-? % "of" 860=210.1`

Options

A. 25
B. 15
C. 20
D. 30

Explanation

To solve the equation \( 65\% \text{ of } 654 - ?\% \text{ of } 860 = 210.1 \), we will follow these steps:

### Step 1: Convert percentages to fractions
We start by converting the percentages into fractions.
- \( 65\% \) can be written as \( \frac{65}{100} \).
- Let \( ? \% \) be represented as \( x \), so \( ?\% \) can be written as \( \frac{x}{100} \).

### Step 2: Set up the equation
We can now rewrite the equation:
\[ \frac{65}{100} \times 654 - \frac{x}{100} \times 860 = 210.1 \]

### Step 3: Calculate \( 65\% \text{ of } 654 \)
Now, we calculate \( 65\% \text{ of } 654 \):
\[ \frac{65 \times 654}{100} = \frac{42510}{100} = 425.1 \]

### Step 4: Substitute back into the equation
Substituting this value back into the equation gives:
\[ 425.1 - \frac{x \times 860}{100} = 210.1 \]

### Step 5: Isolate the term with \( x \)
Now, we will isolate the term with \( x \):
\[ 425.1 - 210.1 = \frac{x \times 860}{100} \]
Calculating the left-hand side:
\[ 215 = \frac{x \times 860}{100} \]

### Step 6: Multiply both sides by 100
To eliminate the fraction, multiply both sides by 100:
\[ 21500 = 860x \]

### Step 7: Solve for \( x \)
Now, divide both sides by 860 to solve for \( x \):
\[ x = \frac{21500}{860} \]
Calculating this gives:
\[ x = 25 \]

### Final Answer
Thus, the value of \( ? \) is \( 25 \).

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