1. **State the problem:** We are given the inequality $$100 + 25x < 150 + 20x$$ where $x$ represents the number of hours a moving job takes. We want to find for which values of $x$ company A (costing $100 + 25x$) is less expensive than company B (costing $150 + 20x$).
2. **Write the inequality and isolate $x$:**
$$100 + 25x < 150 + 20x$$
3. **Subtract $20x$ from both sides:**
$$100 + 25x - 20x < 150 + 20x - 20x$$
$$100 + 5x < 150$$
4. **Subtract 100 from both sides:**
$$100 + 5x - 100 < 150 - 100$$
$$5x < 50$$
5. **Divide both sides by 5:**
$$x < 10$$
6. **Interpretation:** This means company A is less expensive than company B when the job takes less than 10 hours.
7. **Check the boundary:** At $x=10$, costs are equal:
$$100 + 25(10) = 100 + 250 = 350$$
$$150 + 20(10) = 150 + 200 = 350$$
8. **Summary:**
- For $x < 10$, company A is cheaper.
- For $x = 10$, costs are equal.
- For $x > 10$, company B is cheaper.
This helps decide which company to choose based on the job duration.
Cost Inequality
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