a) -1 2/5 * 1 7/8 = -7/5 * 15/8= -21/8= -2 5/8
b) -4 4/5 : (-2 ⅕)= -24/5 : (-11/5)= (-24/5)*(-5/11)=24/11=2 3/11
c) 0,00072 : (-0,9)=72: (-90000)=-72/90000=-8/10000= -1/1250
d) -1,4 * (-4,05)= -1⅖ * (-4 1/20)= -7/5 * (-81/20)=567/100=5 67/100
