(-2 5/9 + 1 20/21) ÷ 1 8/49 - 1 7/9÷(- 6)

(-2 5/9 + 1 20/21) : 1 8/49 - 1 7/9 : (-6) = - 2/9

1) - 2 5/9 + 1 20/21 = -2 35/63 + 1 60/63 = - (1 98/63 - 1 60/63) = - 38/63
2) - 38/63 : 1 8/49 = - 38/63 : 57/49 = - 38/63 * 49/57 = - (2*7)/(9*3) = - 14/27
3) 1 7/9 : (-6) = 16/9 * (-1/6) = - (8*1)/(9*3) = - 8/27
4) - 14/27 - (-8/27) = - 14/27 + 8/27 = - 6/27 = - 2/9