3(19/21) - 4,51 - 5,49 = 3(19/21) - (4,51 + 5,49) = 3(19/21) - 10 = 82/21 - 210/21 = -128/21 = -6(2/21)
-8(3/7) - 1(4/7) - 5(11/14) = -59/7 - 11/7 - 81/14 = -118/14 - 22/14 - 81/14 = (-118 - 22 - 81)/14 = -221/14 = -15(11/14)
-2(17/35) - (-4(2/5)) - (-5,6) = -2(17/35) + 4(2/5) + 5,6 = -87/35 + 22/5 + 56/10 = -87/35 + 154/35 + 196/35 = 263/35 = 7(18/35)