23-(7+4) = 12
87-(34+24) = 29
39-(15-11) = 35
87-34-24 = 29
39-15+11 = 35
23-7-4 = 12
39-(15+11) = 13
23-(7-4) = 20
87-(34-24) = 77
200-77=123 159-88=71