Let x = positive integer and y = negative integer
Then, l x l = x and l y l = -y (Example: l 7 l = 7, l -10 l = 10 = -(-10)
So, x - y = 18 and x = -5y
Therefore, (-5y) - y = 18
-6y = 18 y = -3
x = -5y = -5(-3) = 15