1. **Problem 7:** You save 90 every 2 weeks. How long to save 450? 2. Use the formula: Total saved = (Amount saved per period) \times (Number of periods). 3. Let $n$ be the number of 2-week periods needed. Then: $$90 \times n = 450$$ 4. Solve for $n$: $$n = \frac{450}{90} = 5$$ 5. Since each period is 2 weeks, total weeks: $$5 \times 2 = 10$$ 6. **Answer:** 10 weeks. 7. **Problem 8:** You need 4 red tiles for every 3 blue tiles. You have 360 blue tiles. How many red tiles? 8. Use the ratio formula: $$\frac{\text{red}}{\text{blue}} = \frac{4}{3}$$ 9. Let $r$ be the number of red tiles. Then: $$\frac{r}{360} = \frac{4}{3}$$ 10. Solve for $r$: $$r = 360 \times \frac{4}{3}$$ 11. Simplify: $$r = 360 \times \cancel{\frac{4}{3}} = 360 \times \frac{4}{3}$$ 12. Calculate: $$r = 360 \times \frac{4}{3} = 120 \times 4 = 480$$ 13. **Answer:** 480 red tiles.