1) 7x-4<31
7x<35
x<5
raspuns: d
2)28x<84
x<84/28
x<3
x=1,2,3
3)( a+b+c+d)/4=75
a+b+c+d=75.4=300
4) (a+b+c)/3=655
a=713
a+b+c=655.3=1965
b+c=1965-713
b+c=1252
(b+c)/2=626
5) 123x-1278=5634
123x=6642
x=54
6) 11+12+...+100= (100.101)/2 - (10.11)/2=5050-55=4995
5000x-5=4995
5000x=5000
x=1
7)a+b=120
a=bx4
b.4+b=120
5b=120
b=24
a=96
8)a+b=56
a:b= 3 rest 4
a=3b+4
3b+4+b=56
4b=52
b=13
a=3.13+4=39+4=43
9) notez a= ap cu 2 camere
b= ap cu 4 camere
aici e sistem:
a+b=60
2a+4b=190
din prima ecuatie il scot pe a: a=60-b
il inlocuiesc in a doua: 2(60-b)+4b=190
120-2b+4b=190
2b=190-120
2b=70
b=35 apartamente cu 4 camere
a=60-35=25 apartamente cu 2 camere
