1. **Stating the problem:** Convert 3,450 mL to liters and 1.68 L to milliliters. 2. **Formula and rules:** - 1 liter (L) = 1,000 milliliters (mL). - To convert mL to L, divide by 1,000. - To convert L to mL, multiply by 1,000. 3. **Convert 3,450 mL to L:** $$3,450\ \text{mL} = \frac{3,450}{1,000}\ \text{L}$$ Show cancelation: $$3,450\ \text{mL} = \frac{\cancel{3,450}}{\cancel{1,000}}\ \text{L} = 3.45\ \text{L}$$ 4. **Convert 1.68 L to mL:** $$1.68\ \text{L} = 1.68 \times 1,000\ \text{mL}$$ Calculate: $$1.68 \times 1,000 = 1,680\ \text{mL}$$ **Final answers:** - 3,450 mL = 3.45 L - 1.68 L = 1,680 mL