Page "Twin paradox" Paragraph 36

As for the screen on Earth, it shows that trip back beginning 9 years after launch, and the traveling clock in the screen shows that 3 years have passed on the ship.

One year later, the ship is back home and the clock shows 6 years.

So, during the trip back, both twins see their sibling's clock going 3 times faster than their own.

Factoring out the fact that the light-time-delay is decreasing by 0. 8 seconds every second, each twin calculates that the other twin is aging at 60 % his own aging speed.