Here we have three laser receivers near the exit, and a couple of lasers in the other part of the room, as well as some laser cubes. You have to get the lasers to go into all three laser receivers.

The trouble is that you can only make one pair of portals.

To solve this problem, first create a portal on the column across from the three laser receivers. Then go over to the laser that is hitting the wall and create a portal on the wall that it is shining on. That laser will hit one of the laser receivers.

Now put a laser cube under the laser that is shining from the ceiling. Aim the laser through the portal and into the laser receiver that you can see there.

Finally, take the unused laser cube and walk to a spot where you can look straight through the portal at the laser receiver that you haven't lit up yet. Use the laser cube on the laser coming from the non-angled wall and make it go into the laser receiver that you haven't lit yet. All three laser receivers should be lit up now. Jump over the lasers and go past the laser receivers to the exit door.