Insert your first line as a Shape. Grab the handle at the higher end and drag down to make in a horizontal line.
With that line selected, press command-D to Duplicate it. Selection will pass to the new line.
Repeat command-D until you have the number of lines you want.
The last line will now be 'selected'.
Press and hold command as you click on each of the now unselected lines to add it to the selection.
With all the lines selected, go to the Arrange menu d choose Align Objects > left.
With all the lines still selected, go again to the Arrange menu and choose Group.
Your lines will now have handles at each corner and at the mid point of each side, and will act as a single object.
Click on one of the middle lines, but not on a handle, and drag to place the top line in position on the page.
Click on one of the handles on the bottom line and drag down (or up) to set the spacing between the lines.*
Click anywhere that is away from the object to deselect it.
Regards,
Barry
*The grouped object was set to Constrain Proportions on the version of Pages i used, meaning the lines would change length as the separation between them was increased or reduced.
After settig the spacing between lines as described above, Ungroup the lines (but leave then selected).
In the Arrange section of the Format inspector, use the x size controls to increase or decrease the length of the lines.
B.