1. **State the problem:** The cost of food for a family increases from 41000 to 45000. We need to calculate the amount of money by which the cost has increased. 2. **Formula used:** The increase in cost is given by the difference between the new cost and the original cost. $$\text{Increase} = \text{New Cost} - \text{Original Cost}$$ 3. **Calculate the increase:** $$\text{Increase} = 45000 - 41000 = 4000$$ 4. **Explanation:** The amount of money that the cost of food has increased by is 4000. This means the family needs to pay 4000 more than before for food. **Final answer:** The increase in the cost of food is 4000.