If 4:5:: x:45, then the value of x is

Options

A. 54
B. 60
C. 36
D. 30

Answer

To solve the problem where the ratio 4:5 is equal to the ratio x:45, we can follow these steps:

### Step-by-Step Solution:

1. **Set up the proportion**:
We start with the given ratio 4:5::x:45. This can be expressed as:
\[ \frac{4}{5} = \frac{x}{45} \]

2. **Cross-multiply**:
To eliminate the fractions, we cross-multiply:
\[ 4 \cdot 45 = 5 \cdot x \]

3. **Calculate the left side**:
Now, calculate \(4 \cdot 45\):
\[ 4 \cdot 45 = 180 \]
So, we have:
\[ 180 = 5x \]

4. **Isolate x**:
To find x, we need to isolate it. We do this by dividing both sides of the equation by 5:
\[ x = \frac{180}{5} \]

5. **Perform the division**:
Now, calculate \(180 \div 5\):
\[ 180 \div 5 = 36 \]

6. **Final answer**:
Therefore, the value of x is:
\[ x = 36 \]

### Summary of the Solution:
The value of x is 36.