1. **State the problem:** We are given two angles, $4p$ and $5p$, that are adjacent and together form a right angle (90 degrees). We need to find the value of $p$. 2. **Formula and rule:** The sum of adjacent angles forming a right angle is 90 degrees. So, we use the equation: $$4p + 5p = 90$$ 3. **Solve the equation:** Combine like terms: $$9p = 90$$ Divide both sides by 9: $$p = \frac{90}{9} = 10$$ 4. **Conclusion:** The value of $p$ is 10 degrees. This means the angles are $4p = 40$ degrees and $5p = 50$ degrees, which add up to 90 degrees, confirming the right angle.