Use portals to fling yourself (and the cube) to the button. Now that you're up top, use portals to get the cube up here too.

Oh look, the Companion Cube! Grab it and use it to block the laser, get on the moving platform, and the use portals to remove the cube from blocking the laser so you can go up. Once on the other side press the button twice to get the cube, and drop it onto the button in the far corner with portals. Be sure to setup your portals on the two white ramps. Jump onto the faith plates to bounce across more faith plates all the way to the exit. Use the Faith plates to jump across the room and catch the cube mid air for the button by the door. Use them to jump to the other side and press the button to drop a cube. Time for Aerial Faith plates, stepping on them will send you flying in a controlled arch. Take the cube on the platform to get to the exit (be sure to jump the laser). From there, place the portal you DIDN'T place to the left of the door on the laser to make the platform start moving. Place a portal on the white surface after entering the test, and portal across to the button. Then, use portals to connect the second laser to the other receiver.

Get the redirection cube onto the platform that rose out of the ground and redirect the lower laser with the cube. Go up the stairs and use portals to get the cube up the platform with you. Place the cube so that it redirects the laser into the receiver. This cube will redirect a laser that's pointed at it. Jump over the laser and grab the cube by using portals. Be sure to stand on the moving platform before connecting it. This one is simple, Place a portal under the laser and the other portal above the receiver so the laser goes in. You can jump to nearby pages of the game using the links above.

Portal 2 coop level 7