a) {5-8+3+[6-3+4+(4-7+1)]}+9-7=5
1. 4-7+1=-4
2. 6-3+4-4=3
3. 5-8+3+3=3
4. 3+9-7=5
b) {-2+4+6+[-5+1+2+(-6+9-2)]}+3-8=2 1. -6+9-2=1
2. -5+1+2+1=-1
3. -2+4+6-1=7
4. 7+3-8=2
c) -1+3+{1-3-5+[-7-4+5+(-6+2-4)]}=-19
1. -6+2-4=-8
2. -7-4+5-8=-14
3. 1-3-5-14=-21
4. -1+3-21=-19
d) 10-6+8+{3-6-5+[-1+4-3+(-7+5-2)]}=0
1. -7+5-2=-4
2. -1+4-3-4=-4
3. 3-6-5-4=-12
4. 10-6+8-12=0
e) -2+9+4-6+4-3+[5-3-6+(7-9-1)]=-1
1. 7-9-1=-3
2. 5-3-6-3=-7
3. -2+9+4-6+4-3-7=-1
f) -7+2+5+{-1+4-2+[-3+6-5+(-9+8-2)]}=-4
1. -9+8-2=-3
2. -3+6-5-3=-5
3. -1+4-2-5=-4
4. -7+2+5-4=-4