1. **State the problem:** There are 90 kids in the band. 20% of the kids own their own instruments, and the rest rent them. We need to find how many kids own their own instruments. 2. **Formula used:** To find a percentage of a quantity, use the formula: $$\text{Part} = \frac{\text{Percentage}}{100} \times \text{Total}$$ 3. **Apply the formula:** Here, the percentage is 20%, and the total number of kids is 90. $$\text{Number of kids who own instruments} = \frac{20}{100} \times 90$$ 4. **Calculate:** $$= 0.20 \times 90$$ $$= 18$$ 5. **Interpretation:** So, 18 kids own their own instruments. **Final answer:** 18 kids own their own instruments.