a) 4+[4-(4+4:4x4-4)+a]:4 = 8
[4-(4+1x4-4)+a]:4 = 8-4 = 4
4-(4+4-4)+a = 4x4 = 16
4-4+a = 16
a = 16
b) 8+6x;[4+27:(0+ux9)] = 49+10:10
8+6x[4+27:(ux9)] = 49+1 = 50
6x[4+27:(ux9)] = 50-8 = 42
4+27:(ux9) = 42:6 = 7
27:(ux9) = 7-4 = 3
ux9 = 27:3 = 9
u = 1
c) 0+[(1+2x3):c+5]:6 = (78-69):9
[(1+6):c+5]:6 = 9:9 = 1
7:c + 5 = 1x6 = 6
7:c = 6-5 = 1
c = 7:1 = 7
c = 7
d) 88:2:4 + 10xe = 99+6:3
44:4 + 10xe = 99+2
11 + 10xe = 101
10xe = 101-11 =90
e = 90:10
e = 9