1. **Problem:** Write the ratio 75 to 100 in simplest form. 2. **Formula:** To simplify a ratio, divide both terms by their greatest common divisor (GCD). 3. **Step 1:** Find the GCD of 75 and 100. $$\text{GCD}(75, 100) = 25$$ 4. **Step 2:** Divide both terms by 25. $$\frac{75}{\cancel{25}} : \frac{100}{\cancel{25}} = 3 : 4$$ 5. **Answer:** The simplest form of the ratio 75 to 100 is $3 : 4$.