Express the ratio 2.5:6.5:8 in simplest form:

To simplify the given ratio \( 2.5 : 6.5 : 8 \), follow these steps:

1. **Convert all terms into whole numbers**:
Ratios are easier to simplify when all terms are whole numbers. To do this, multiply each term by 10 (since the decimals have one digit after the decimal point). This gives:
\( 2.5 \times 10 : 6.5 \times 10 : 8 \times 10 = 25 : 65 : 80 \).

2. **Find the greatest common divisor (GCD)** of the terms:
- The numbers are \( 25, 65, \) and \( 80 \).
- The prime factorization of these numbers is:
\( 25 = 5^2 \),
\( 65 = 5 \times 13 \),
\( 80 = 2^4 \times 5 \).
- The common factor among all terms is \( 5 \).

3. **Divide each term by the GCD (5)**:
\( \frac{25}{5} : \frac{65}{5} : \frac{80}{5} = 5 : 13 : 16 \).

4. **Simplified ratio**:
The simplest form of the ratio is \( 5 : 13 : 16 \).

Thus, the ratio \( 2.5 : 6.5 : 8 \) in simplest form is **5 : 13 : 16**.