If -4 is added to a number and them sum is doubled, the result is -16 less than the number. find the number.

Let the number be x
(-4+x)×2 = x-(-16)
-8-2x=x+16
-2x-x=16+8
-3x=24
x=24÷-3
x=-8

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.