((15/28-11/36)*21/29-6 6/7: (-16/21)): (-16,5)

((15/28 - 11/36) * 21/29 - 6 6/7 : (-16/21)) : (-16,5) = - 5/9
1) 15/28 - 11/36 = 135/252 - 77/252 = 58/252 = 29/126
2) 29/126 * 21/29 = 21/126 = 1/6
3) 6 6/7 : (-16/21) = 48/7 * (-21/16) = - 9
4) 1/6 - (-9) = 1/6 + 9 = 9 1/6
5) 9 1/6 : (-16,5) = 55/6 : (-165/10) = 55/6 * (-10/165) = - 5/9