adding or subtracting depending on the number

How do I make it so that if a random number is above a certain amount a number will be subtracted from a diffrent variable. But if the random number is below a certain amount it will be added to a variable.

[David Hill]

What have you tried? Can you explain yourself better through a code example?

Answer 1

[Torsten]

rng ("default")
amount = 0.5;
variable = 5;
number = 1;
r = rand;
if r >= amount
    variable = variable - number;
else
    variable = variable + number;
end
variable

variable = 4

Answer 2

[Walter Roberson]

Variable = Variable + sign(Threshold - RandomNumber) * amount