А .....= - 13,1 - 1,9 - 6,7= - 21,7
Б .....=8 6/18 - 8/18+5/18=8 3/18=8 1/6
В .....= - 1 48/56 +32/56 - 2 21/56= - 3 37/56
Г ......=20 5/12+4/12-11/12=19 10/12=19 5/6
Д .....=11 5/8+3/8 +5 2/8=12+5 2/8=17 1/4
Е .....= - 16 23/42+11/42 - 30/42= - 16 42/42= - 17
2.
-(m-a)-(k+a)= - m+a-k-a= - m - k
- 0.16+4.06 - m=3.9 - m