HI
As an alternative you can drag the clip you want to slow down to a higher track (an empty one), then change the speed when it will now overlap the main track and you can see how far it extends.
Now select all the clips on the main track and drag them along to the right beyond the end of the slo mo clip. Pull the slow mo clip back down again into the space you madeand close the gap.The video should all now be on the main track again.
This method allows you to see where the slo-mo clip ends, you don't have to guess how far to move the main track clips. It';s academic really as both methods work just fine.
Nat