1. **Problem:** Simplify the ratio 36:90 to its lowest terms. 2. **Formula:** To simplify a ratio, divide both terms by their greatest common divisor (GCD). 3. **Work:** - Find GCD of 36 and 90: GCD(36, 90) = 18. - Divide both terms by 18: $$\frac{36}{\cancel{18}} : \frac{90}{\cancel{18}} = 2 : 5$$ 4. **Explanation:** The ratio 36:90 simplifies to 2:5 because both numbers share a common factor 18. **Final answer:** 2:5 **Notes for exam review:** - To simplify ratios, always find the greatest common divisor. - Divide both parts of the ratio by the GCD to get the simplest form. - Ratios express a relationship between two quantities.