According to the second condition, the sum of the figures on the opposite sides of the cube is equal to 7. At this time, imagine the unfolding of a cube folded into a cube and know the numbers on each side. (You can draw pictures first, then master them and build them in your mind, that is, spatial logical thinking)
According to the last sentence, there may be many schemes, so the correct cube expansion diagram can be directly verified at the beginning, and it is suggested to think of several expansion diagrams.
Emm…… ............................................................................................................................................................................... If the method is wrong, I will gain something (just a personal idea).
The answer is not easy, please accept it. Thank you.