To find the length \( l \) of the garden, we can start with the equation for the perimeter given by:
\[ P = 2l + 2w \]
We know the perimeter \( P \) is 24 feet and the width \( w \) is 6 feet. Plugging these values into the equation gives us:
\[ 24 = 2l + 2(6) \]
Now, let's simplify the equation:
\[ 24 = 2l + 12 \]
Next, we need to isolate \( 2l \). We can do this by subtracting 12 from both sides:
\[ 24 - 12 = 2l \]
This simplifies to:
\[ 12 = 2l \]
Now, to find \( l \), we divide both sides by 2:
\[ l = \frac{12}{2} \]
This gives:
\[ l = 6 \text{ feet} \]
So the length of the garden is 6 feet.