1. The problem is to add the two numbers $0.2$ and $5.9$. 2. The formula for addition is $a + b = c$, where $a$ and $b$ are the numbers to add, and $c$ is the sum. 3. Here, $a = 0.2$ and $b = 5.9$. 4. Add the numbers: $$0.2 + 5.9 = 6.1$$ 5. So, the sum of $0.2$ and $5.9$ is $6.1$.