a)80:(74:2-a:4)=5
80:(37-a:4)=5
37-a:4=80:5
37-a:4=16
a:4=37-16
a:4=21
a=21x4
a=84
(73:3x8+16x8+2xXx2):12=29
73:3=24.33
(24.33x8+128+2xX2x2):12=29
(194.64+128+2xXx2):12=29
(322.64+2xX2x):12=29
322.64+2xX2=29x12=348
2xX2x=348-.322.64=25.36
2xXx2=25.36
2x=25.6:2=12.68
x=12.68:2=6.34
daca ai scris gresit in loc de 72 ai scris 73 avem asa
(72:3x8+16x8+2xXx2):12=29
(192+128+2xXx2):12=29
320+2xX2=29x12=348
2xX2=340-320=20
2x=20:2=10
x=10:2
x=5
