3//7(-0,54)-1,56*3//7
3/7*(-0,54)-1,56*3/7 = 3/7 * (-0,54-1,56) = 3/7 * (-2,1) = - 3/7*21/10= -63/70
3//7(-0,54)-1,56*3//7= 3/7 •(-0,54-1,56)=3/7•(-2,1)=3/7•(-21/10)=- 9/10 =-0,9