(2 1/2 + 1 1/3): (1/6 - 5 3/7) = -161/221
1) 2 1/2 + 1 1/3 = 2 3/6 + 1 2/6 = 3 5/6
2) 1/6 - 5 3/7 = -(5 3/7 - 1/6) = -(5 18/42 - 7/42) = -5 11/42
3) 3 5/6 : ( -5 11/42) = -(23/6 : 221/42) = -(23·42:(6·221)) = -(23·7:221) = -161/221
(2 1/2 + 1 1/3): (1/6 - 5 3/7) = -161/221
1) 2 1/2 + 1 1/3 = 2 3/6 + 1 2/6 = 3 5/6
2) 1/6 - 5 3/7 = -(5 3/7 - 1/6) = -(5 18/42 - 7/42) = -5 11/42
3) 3 5/6 : ( -5 11/42) = -(23/6 : 221/42) = -(23·42:(6·221)) = -(23·7:221) = -161/221