Răspuns :
[(x+90)x7-100]:4=30x5 [(x+90)x7-100]:4=150 [(x+90)x7-100]=150x4 [(x+90)x7-100]=600 (7x+630-100)=600 7x+530=600 7x=600-530 7x=70 x=70:7 x=10