The difference between the opposite of a number and 6.
The phrase a number means an arbitrary variable, let's call it x.
x
The opposite of a number means we multiply by x by -1
-x
The phrase the difference between means we subtract 6 from -x:
-x - 6
The phrase a number means an arbitrary variable, let's call it x.
x
The opposite of a number means we multiply by x by -1
-x
The phrase the difference between means we subtract 6 from -x:
-x - 6