Express the ratio in simplest form :
`20: 40`

Answer

To express the ratio 20:40 in its simplest form, we can follow these steps:

### Step 1: Write the Ratio
We start with the given ratio:
\[ 20 : 40 \]

### Step 2: Find the Greatest Common Factor (GCF)
Next, we need to find the greatest common factor (GCF) of the two numbers, 20 and 40. The factors of 20 are:
- 1, 2, 4, 5, 10, 20

The factors of 40 are:
- 1, 2, 4, 5, 8, 10, 20, 40

The greatest common factor between 20 and 40 is:
\[ 20 \]

### Step 3: Divide Both Numbers by the GCF
Now, we divide both parts of the ratio by the GCF:
\[ \frac{20}{20} : \frac{40}{20} \]
This simplifies to:
\[ 1 : 2 \]

### Step 4: Write the Final Answer
Thus, the simplest form of the ratio 20:40 is:
\[ 1 : 2 \]

### Summary
The simplest form of the ratio 20:40 is \( 1:2 \).

---