What number and the sum of minus 5 / 12 are equal to - 1

What number and the sum of minus 5 / 12 are equal to - 1

-The sum of 1 - (- 5 / 12) = - 1 + 5 / 12 = - 7 / 12-7 / 12 and minus 5 / 12 equals - 1