1) 1/4=0.25, 0.25-0.2=0.05 или 0.2=2/10=1/51/4 -1/5 =(5-4)/20=1/20=0.2
2) -3/7 +1/5 =(-3*5+7) / 35= (-15+7) /35 = -8/35
3) 1.5=1 5/10=1 1/2=3/2-1/3 * 3/2= (-1*3)/3*2 = -3/6 = -1/2 = -0.5
4) при делении дробь переворачиваем и будет умножение 0.36=36/100=9/259/25 *(-19/18) =(-9*19)/(25*18) = -19/25*2 = -19/50 = -0.38
5) 3 1/2=7/2=3.52.3=23/10-7/2 + 23/10=(-7*5+23)/10 = (-35+23)/10= -12/10= -1.2или -3.5 +2.3= -1.2
6) 2 1/3=7/3, 4.1=41/107/3 - 41/10 =(70-123)/30 == -53/10 = -5.3
7) 1 6/10=1 3/5=8/511/4 * 8/5=11*8 / 4*5 =22/5 =4.4
8) 1 1/4=5/4, 6.25=6 25/100 = 6 1/4 =25/4-25/4 * 4/5 = -25*4 / 4*5 = -5
9) 3 19/20=79/205 1/5=26/55.25=5 1/4=21/41.4=1 4/10=1 2/5=7/5-21/4 : (26/5 -(5/7 *7/5) - 79/20 = -21/4 : (26/5 -1) - 79/20= -21/4 : 21/5 - 79/20 = -21/4 * 5/21 - 79/20 == -5/4 - 79/20 =(-25-79)/20 = -104/20= -5.2