So, another way to think about subtraction is how far apart two numbers are, buuuuut we measure distance using positive numbers (why absolute value is always positive).
Because it says "5 units from m" but doesn't say which direction, that's |m - 5|.
|20 - 5| = 15 because they are 15 apart.
|-20 - 5| = 25 because they are 25 apart.
x > |m - 5|