Answer :

Answer:

  9

Step-by-step explanation:

Given the width of a rectangle varies inversely with its length, you want to know the width when the length is 8, given the width is 4 when the length is 18.

Inverse relation

When L and W vary inversely, we have ...

  W = k/L . . . . for some constant k

Multiplying by L gives ...

  W·L = k

Then we have ...

  4 · 18 = k = W · 8 . . . . . using the given values

Dividing by 8 gives ...

  W = 9 . . . . . . . . . . . . . . . . the width is 9 when length is 8.

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Additional comment

This tells you the area of the rectangle is a constant, 72 square units.