Then 2 16=x(24-x/2)

Then 24x-x 2/2 = 2 16.

Then (x-24) 2 = 144.

X-24= 12。

Then x=36.

Then 24-x/2=6.

36 is greater than 30

Choose 30 meters as the wall.

30x=2 16

X = 7.2m。

Then the fence used 2x7.2+30-1= 43.4m..