1. **State the problem:** Bill drives 320 km each week. His car consumes 7 liters of gas per 100 km, and gas costs 1.02 per liter. We need to find his weekly gas expense. 2. **Formula used:** Gas consumption per week = $\frac{7}{100} \times 320$ liters Weekly gas expense = Gas consumption per week $\times$ cost per liter 3. **Calculate gas consumption:** $$\frac{7}{100} \times 320 = \frac{7 \times 320}{100} = \frac{2240}{100} = 22.4 \text{ liters}$$ 4. **Calculate weekly gas expense:** $$22.4 \times 1.02 = 22.4 \times (1 + 0.02) = 22.4 + 0.448 = 22.848$$ 5. **Answer:** Bill's weekly gas expense is **22.848** (units of currency).