91, 93, 97, 98, 99, 106

5ռ-x

10ռ-y

{5x+10y=70

{x+y=10

x=10-y

5(10-y)+10y=70

50-5y+10y=70

5y=20

y=20/5=4

x=10-4=6

I թիվ-x

II թիվ-y

{x+y=31

{x-y=5

x=5+y

5+y+y=31

2y=31-5

2y=26

y=26/2=13

x=5+13=18

I թիվ-x

II թիվ-y

{5x/100+4y/100=46

{4x/100+5y/100=44

5x+4y=4600

4x+5y=4400

20x+16y=18400

20x+25y=22000

20x-20x=0

25y-16y=22000-18400

9y=3600

y=3600/9=400

4x+2000=4400

4x=4400-2000=2400

x=2400/4=600

I թիվ-x

II թիվ-y

{20x/100+50y/100=27

{50x/100+50y/100=42,3

20x+50y=2700

50x+50y=4230

50y-50y=0

30x=1530

x=1530/30=51

1020+50y=2700

50y=2700-1020=1680

y=1680/50=33,6

AC=16սմ

BC-AB=0,4դմ=4սմ

AB+BC+AC=38

AB+BC+16=38

{AB+BC=22

{BC-AB=4

AB-AB=0

2*BC=26

BC=26/2=13

AB+13=22

AB=22-13=9

Բ-x

Ս-y

{3x+4y=2500գ

{4x+3y=2400գ

12x+16y=10 000գ

12x+9y=7200գ

12x-12x=0

7y=2800գ

y=2800/7=400

12x+3600=7200գ

12x=7200-3600=3600

x=3600/12=300