1.(-2.5)+(-5.9)
= -8.4
2.1.9+6
= 7.9
3.(-4.2)+(-8.4)+5.7+10
=(-12.6)+10
= -2.6
4.(-3.7)+(-4.9)+6.1+1.8
=(-8.6)+7.9
=-0.7
5.1/3-2/3+1
=1/3+1-2/3
= 2/3
6.(-1/4)+5/6+2/3-1/2
=(-1/4)+(-1/2)+5/6+2/3
=(-3/4)+9/6
=3/4
7.-36-25-36+72
=-97+72
=-25
8.-8+3+5-9
=-17+8
=-9
9.-5-9+3
=-11
10.-5-9+3
=-11
11.-3-4+19-11
=1
12.-8+12-16-23
=-35