1) 3 4/5 * 1 1/19= 19/5 * 20/19 = 4 2) 4-25/6= 4/1 - 25/6= 24/6 - 25/6 = 24-25/6=-1/6 3) -1,6 : 3,5= -1,6 : 35/10= -1/6 * 10/35= -1/3 * 5/35= -5/105 = -1/21