-2,8+(-1,65+(-3/4))= -2,8+(-1,65-0,75)= -2,8+(-2,4)= -5,2
-8+4 3/7+2 11/21= -8+4 9/21+2 11/21= -8+6 20/21= -1 1/21
2,2+(-4 1/3)+(-1 13/15)= 2,2+(-13/3)+(-28/15)= 2,2-4,3-1,87= -3,97
-2,8+(-1,65+(-3/4))
= -2,8+(-1,65-0,75)
= -2,8+(-2,4)
= -5,2
-8+4 3/7+2 11/21
= -8+4 9/21+2 11/21
= -8+6 20/21
= -1 1/21
2,2+(-4 1/3)+(-1 13/15)
= 2,2+(-13/3)+(-28/15)
= 2,2-4,3-1,87
= -3,97