To solve the equation $4x + 9 = 40$, follow these steps:

1. Subtract 9 from both sides to isolate the term with $x$: $4x + 9 - 9 = 40 - 9$ $4x = 31$

2. Divide both sides by 4 to solve for $x$: $x = \frac{31}{4}$ $x = 7.75$

Thus, the solution is $x = 7.75$.

Would you like further clarification or details? Here are five related questions to explore:

1. What if the equation was $5x + 9 = 50$?
2. How do you solve $4x + 9 = 0$?
3. What happens if $4x + 9 = -40$?
4. Can you solve $4x + 9 = 31 + 9x$?
5. How would you check if $x = 7.75$ is correct?

Tip: Always remember to perform the same operation on both sides of the equation when solving for a variable.