Answer:
No. |m| can only be positive.
Step-by-step explanation:
Absolute value |m| indicates magnitude, i.e. it has no "direction". m=-18 indicates that m is 18 units left (negative) of position 0; it has direction. |m| asks for the value of m without any direction, i.e. its magnitude.
If it was: |m|=18 then the rest would be true.
See also magnitude vs vectors.
