1. The problem involves converting volumes and understanding the relationships between different units such as milliliters (ml) and liters (L). 2. Recall the basic conversion: $$1\text{ L} = 1000\text{ ml}$$. 3. Given: $$500\text{ ml} \to 2a/0.1$$. Let's interpret this as converting 500 ml to some unit involving $a$. 4. Since $$500\text{ ml} = 0.5\text{ L}$$, if $$0.5\text{ L} = \frac{2a}{0.1}$$, then multiply both sides by 0.1: $$0.5 \times 0.1 = 2a$$ $$0.05 = 2a$$ 5. Divide both sides by 2 to solve for $a$: $$\frac{0.05}{\cancel{2}} = \frac{2a}{\cancel{2}}$$ $$0.025 = a$$ 6. Therefore, $$a = 0.025$$. 7. Other given values like $$5000\text{ ml} / 100$$ simplify to: $$\frac{5000}{100} = 50$$ 8. For $$5\text{ L} \to 29 w i D$$ and $$0.10\text{ L} = 20$$, without further context or definitions for $w$, $i$, $D$, or the meaning of arrows, these cannot be precisely calculated. Final answer for $a$: $$a = 0.025$$