1. (5x4) : (2+8)-2=0
2. 7-[5200:13-5 ×(360-2 × x)]:20=2
-[400-5 ×(360-2 × x)]:20=2-7
-[400-5 ×(360-2 × x)]:20=-5
[400-5 ×(360-2 × x)]=5×20
-5 ×(360-2 × x)=100-400
-5 ×(360-2 × x)=-300
5 ×(360-2 × x)=300
(360-2 × x)=300:5
360-2 × x=60
-2 × x=60-360
-2 × x=-300
2 × x=300
x=300:2=150
3. a+3a=2048
4a=2048
a=512
4)
a=varsta tata
b=varsta unui copil
a+2b=39 a=39-2b
a+5=(b+5+b+5)×2
a+5=4b+20
39-2b+5=4b+20
6b=24
b=4 ani are fiecare dintre gemeni
a=39-2×4=31 ani are tatal
5.
a=(b+c)/2
b:c=5 si rest 20 b=5c+20
a=(5c+20+c)/2=(6c+20)/2=3c+10
a+b+c=94539
3c+10+5c+20+c=94539
9c=94539-30
9c=94509
c=10501
a=3×10501+10=31513
b=5×10501+20=52525
