The sum of the 2 integers is -112. if one of them is -109 find the other

let x and be the two integers

x+y=-112

if one of them is -109

let x be one of the that is substitute-109 to the above equation

-109+y=-112

collect like terms to the left hand side.

-109+112=-y

3=-y

move the sigh to the constant

y=-3