stretch div acording to upper div

<div>
<table id = "stretching1">
....
</table>
<div>

<div>
<table id = "stretching2">
....
</table>
<div>



tables shrinks to minimum by default, if upper comes out 300 px, I would like
to have stretching2 of equal width than stretching1

but not wrapped all this into fixed width div !

Can this be done some way.

Can't you just put those two tables inside a single div instead of two separate ones?

it would be the same , one would be lets say 300px wide, the other 200 px,
unless I would applay fixed width to outer div, and 100% width to tables.

The underlined thing is that I don't want to.