1. b){8+66:[100-(80:4+45:5)-5]}×28
={8+66:[100-(20+9)-5]}×28
=[8+66:(100-29-5)]×28
=(8+66:66)×28
=9×28
=252
2.[45:(34-a)+44]:7=7
45:(34-a)+44=49
45:(34-a)=5
34-a=9
a=34-9
a=25
3.
x+(x+1)+(x+2)=90
3x+3=90
3x=87
x=87:3
x=29 primul număr
29+(29+1)+(29+2)=29+30+31=59+31=90
4.a+b=250
a:b=6
a=250-b
_______
a+b=250
=>250-b+b=250
=>2b=0
=>b=0
a+b=250
a+0=250
a=250
5.
24=6-4×a
30+4=a
34=a
a=34
