4) 1,512 : (- 0,27) = - 5,6
5) - 42/55 : (- 98/99) = (-42/55) * (-99/98) = (-6/5) * (-9/14) = 54/70 = 27/35
6) - 1 1/27 : 7 7/9 = - 28/27 : 70/9 = - 28/27 * 9/70 = - 28/210 = - 2/15
1.545:1.5 =1.03
1.03-1=0.3
-2.2/3 ×0.3 = -4/5
-0.5 × 4/5 =-2/15
-4/5-2/15 =-12-2/15 =-2/3