- 7/12 - (5/18 - 11/24) = - 7/12 - (15/48 - 22/48) = - 7/12 + 7/48 = - 28/48 + 7/48 = - 21/48 = - 7/16
- 11/8 - [- 5/24 + (7/36 - 5/48)] = - 11/8 - { - 5/24 + (42/144 - 15/144)] = - 11/8 - [ - 5/24 + 27/144] = - 11/8 - [ - 30/144 + 27/144] = - 11/8 + 3/144 = - 198/144 + 3/144 = - 195/144 = - 63/48 = - 21/16
