Answer:
1 & 3 correct, not sure how race method is used but it should be enough
Step-by-step explanation:
1 is correct since when you add 3 to -3 you get zero and leaves x on the left of the equal sign. then it's equally on both side so you add 3 to 6
2 isn't correct, -3-3 gives -6 and x-6=3 won't give much of an answer
3 is also correct. You basically think "a number that's 6 when you take away 3? could it be 9?" then you try and go 9-3? yes it's 6.