Răspuns:
57-47=10 11+37=48 489-156= 3 3 3
ex 11 a+47=57 a=57-47 a=10
ex 12 b-11=37 b=37+11 b=48
ex 13 a=411-298 a =113
b=653-338 b=315
u= 368+267 u=635
ex 14 a+145=682
a=682-154
a= 528
