2) (-2,5 - 1.5/6) ÷ 1.4/9 - 3.5/9 × (-2.1/4) = (-25/10 - 11/6) ÷ 13/9 - 32/9 × (-9/4) = (-75/30 - 55/30) ÷ 13/9 + 8 = -130/30 × 9/13 + 8 = -90/30 + 8 = -3 + 8 = 5.
3) (-3,8 + 2.1/3) × (-1.7/8) + 4.1/4 ÷ (-1.2/3) = (-38/10 + 7/3) × (-15/8) + 17/4 ÷ (-5/3) = (-114/30 + 70/30) × (-15/8) + 17/4 × (-3/5) = 44/30 × 15/8 + 17/4 × (-3/5) = 44/16 - 51/20 = 11/4 - 51/20 = 55/20 - 51/20 = 4/20 = 1/5.