To determine how far the firework will travel before it reaches the ground, we need to solve the equation \( h(x) = 0 \):
\[ 0 = -x^2 + 15x \]
We can rearrange this equation:
\[ x^2 - 15x = 0 \]
Now, we can factor out an \( x \):
\[ x(x - 15) = 0 \]
Setting each factor equal to zero gives us:
- \( x = 0 \)
- \( x - 15 = 0 \) which simplifies to \( x = 15 \)
Thus, the firework will hit the ground when \( x = 0 \) (the starting point) and \( x = 15 \) feet.
Therefore, the firework will travel 15 feet before it reaches the ground.
Final answer: 15 feet