Răspuns :
[(a-15)x2-4]:11+12=18
[(a-15)x2-4]:11=18-12
[(a-15)x2-4]:11=6
(a-15)x2-4=6x11
(a-15)x2-4=66
(a-15)x2=66+4
a-15=70:2
a-15=35
a=35+15
a=50
[(a-15)x2-4]:11=18-12
[(a-15)x2-4]:11=6
(a-15)x2-4=6x11
(a-15)x2-4=66
(a-15)x2=66+4
a-15=70:2
a-15=35
a=35+15
a=50