40% of 400 + ?% of 300 = 250

Options

A. 40
B. 36
C. 25
D. 30

Answer

To solve the equation \( 40\% \text{ of } 400 + ?\% \text{ of } 300 = 250 \), we can follow these steps:

### Step 1: Calculate \( 40\% \text{ of } 400 \)
To find \( 40\% \text{ of } 400 \):
\[ 40\% = \frac{40}{100} = 0.4 \]
\[ 0.4 \times 400 = 160 \]

### Step 2: Set up the equation
Now, we can rewrite the original equation:
\[ 160 + ?\% \text{ of } 300 = 250 \]

### Step 3: Calculate \( ?\% \text{ of } 300 \)
Let \( ?\% \) be represented as \( x \):
\[ x\% \text{ of } 300 = \frac{x}{100} \times 300 = 3x \]
So, we can rewrite the equation as:
\[ 160 + 3x = 250 \]

### Step 4: Isolate \( 3x \)
Subtract \( 160 \) from both sides:
\[ 3x = 250 - 160 \]
\[ 3x = 90 \]

### Step 5: Solve for \( x \)
Now, divide both sides by \( 3 \):
\[ x = \frac{90}{3} = 30 \]

### Conclusion
Thus, the value of \( ? \) is \( 30 \).