On the top, the cube root of `1000` is `10`.

On the bottom of the fraction, we have a negative index. We need to recall the following 2 properties of fractions and negative indices:

`1/a=a^(-1)`

If the number on the bottom has a negative index, for example negative `1`, then this is the result:

`1/x^(-1)=1/(1text(/)x)=1/(1text(/)x)xxx/x=x`

So `400^(−1//2` on the bottom becomes `400^(1//2` on the top.

And `400^(1//2) =sqrt(400)= 20`.

Here's the complete answer:

`1000^(1text(/)3)/(400^(-1text(/)2)) =10 xx 400^(1 text(/)2)` `=10 xx 20` `=200`