Introduction:
In this question, we are given two weights, 1.8 kg and 6 kg, and we need to find the ratio between them in the simplest form. A ratio compares two quantities and shows how many times one quantity is greater or smaller than the other.

Step 1: Convert the weights into the same unit:
Since the given weights are already in kilograms, we don't need to convert them into the same unit.

Step 2: Write the ratio:
To write the ratio, we divide the larger weight by the smaller weight. In this case, the larger weight is 6 kg and the smaller weight is 1.8 kg. So, the ratio can be written as:

6 kg ÷ 1.8 kg

Step 3: Simplify the ratio:
To simplify the ratio, we need to divide both the numerator and denominator by their greatest common divisor (GCD). In this case, the GCD of 6 and 1.8 is 0.6.

Dividing both the numerator and denominator by 0.6, we get:

6 kg ÷ 0.6 ÷ 1.8 kg ÷ 0.6

Simplifying further, we have:

10 ÷ 3

Step 4: Write the simplified ratio:
The simplified ratio is 10 ÷ 3.

Therefore, the ratio between 1.8 kg and 6 kg in the simplest form is 10 ÷ 3.

Conclusion:
The ratio between 1.8 kg and 6 kg in the simplest form is 10 ÷ 3. This means that the larger weight is approximately 3.33 times greater than the smaller weight.