First, let's simplify the equation:

216 ÷ x + 16 · 18 = 324
18/x + 288 = 324
18/x = 36

Now, multiply both sides of the equation by x:

18 = 36x

Finally, isolate x by dividing both sides by 36:

x = 18/36
x = 0.5

Therefore, the value of x is 0.5.