True because the colonists
Start with multiplying 4*7 to get 28
The equation simplifies to 28=3(2x-5)
Next, multiply the three into (2x-5), leaving the equation as 28=6x-15
After that, add fifteen to 28, getting 42=6x
Next, divide 42 by 6, getting x=7
I believe they were called "dream palaces" because everything seems possible in films/movies and you can use your imagination while in there.
Hope this helps :)