What comes at the place of question (?) mark :
26% of 250 + ?% of 640 = `(15)^(2)`

Options

A. 35
B. 25
C. 20
D. 15

Answer

To solve the equation \( 26\% \text{ of } 250 + ?\% \text{ of } 640 = 15^2 \), we can follow these steps:

### Step 1: Calculate \( 15^2 \)
First, we need to calculate \( 15^2 \):
\[ 15^2 = 225 \]

### Step 2: Calculate \( 26\% \text{ of } 250 \)
Next, we calculate \( 26\% \text{ of } 250 \):
\[ 26\% \text{ of } 250 = \frac{26}{100} \times 250 = \frac{26 \times 250}{100} = \frac{6500}{100} = 65 \]

### Step 3: Set up the equation
Now we can set up the equation:
\[ 65 + ?\% \text{ of } 640 = 225 \]

### Step 4: Isolate the \( ?\% \text{ of } 640 \) term
Subtract 65 from both sides:
\[ ?\% \text{ of } 640 = 225 - 65 = 160 \]

### Step 5: Express \( ?\% \text{ of } 640 \)
Now, express \( ?\% \text{ of } 640 \):
\[ ?\% \text{ of } 640 = \frac{?}{100} \times 640 \]

### Step 6: Set up the equation for \( ? \)
Now we can write:
\[ \frac{?}{100} \times 640 = 160 \]

### Step 7: Solve for \( ? \)
To isolate \( ? \), multiply both sides by 100:
\[ ? \times 640 = 160 \times 100 \]
\[ ? \times 640 = 16000 \]
Now divide both sides by 640:
\[ ? = \frac{16000}{640} \]
Calculating the right side:
\[ ? = 25 \]

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