I am sure this is a personal question, what do you think you would see if you would be able to travel within the multiverse, no one can answer that for you its your opinion :)
For #6, x=-3, add 4 to both sides, divide by 2. #7 is 8, #8 is 3, #9 is 3, #10 is -5.
(3x5)X2=5x(2x3)
15x2=5x6
30=30
If AB is 6 and AC is 4. Look at how BC it longer than AC but shorter than AB. The number in between would be 5 so the answer is 5cm.