Question

15-{5-3+[8-(-1-3)+5]}

Answer 1

15 - {5 - 3 + [8 - (-1 - 3) + 5]} => 15 - {5 - 3 + [8 + 4 + 5]} => 15 - {5 - 3 + 17} => 15 - 19 = -4.