(a)
The sum of a number and 12 can be represented by "x + 12".
If this sum is at most 8, that means it is lesser than or equal to 8, so we have:
[tex]x+12\leq8[/tex](b)
A number increased by 8 can be represented by "x + 8".
If this sum is greater than 12, we have:
[tex]x+8>12[/tex](c)
8 less than a number can be represented by "x - 8".
If this difference is no more than 12, that means it is lesser than or equal to 12, so we have:
[tex]x-8\leq12[/tex]