63% of a number is 315. What is the number?
(a)500
(b)420
(c)475
(d)450

Options

A. 500
B. 420
C. 475
D. 450

Answer

To solve the problem, we need to find the number (let's call it \( x \)) such that 63% of \( x \) equals 315.

### Step-by-Step Solution:

1. **Set up the equation**: We know that 63% of \( x \) is equal to 315. This can be written as:
\[ 0.63x = 315 \]

**Hint**: Remember that "percent" means "per hundred," so 63% can be converted to a decimal by dividing by 100.

2. **Isolate \( x \)**: To find \( x \), we need to isolate it on one side of the equation. We can do this by dividing both sides of the equation by 0.63:
\[ x = \frac{315}{0.63} \]

**Hint**: When isolating a variable, you can perform the same operation on both sides of the equation.

3. **Calculate \( x \)**: Now we perform the division:
\[ x = \frac{315}{0.63} = 500 \]

**Hint**: When dividing, ensure that you perform the calculation accurately. You can use a calculator for precise results.

4. **Conclusion**: The number is \( 500 \).

### Final Answer:
The number is \( 500 \), which corresponds to option (a).