Yes, it is a rational number.
1/12 does not belong with the others because you can simplify the others, but not 1/12
None, because you need to make over 15,000 a year to be taxed. And with all that money for one year would not be taxed.
A number is less than 4 units from 0
-4<x<4
7:
3/8 = 6/x
3x = 48
x = 16
8:
4/5 = (x+7)/40
160 = 5x + 35
5x = 125
x = 25
9:
3/8 = 12/(x-3)
3x - 9 = 96
3x = 105
x = 35
10:
4/1 = (3x+6)/x
4x = 3x + 6
x = 6