Հանրահաշիվ

 80;

Ա)
{x=y+6
{x+y=40
{2y+6=40
{2y=34
y=17
x=17+6=23
Բ)
{x=y+15
{x+y=23
{2y+15=23
{2y=8
y=4
x=4+15=19

82;

Ա)
{x=y+7
{2y+6x=31
{8y+42=31
{8y=-11
y=-1.375
x=7+(-1.375)=5.625
Բ)
{x=y+10
{x/3+y=70
{y+10/3+y=70
{4y+10/3=70
{4y+10=3*70=210
{4y=200
y=50
x=50+10=60

84;

Ա)
{x=y-5
{x+y=61
{y-5+y=61
{2y=66
y=33
x=28
Բ)
{x=y+18
{x+y=66
{2y+18=66
{2y=48
y=24
x=24+18=42

86

{x= y+33
{x+y=57
{2y+33=57
{2y=24
y=12
x=12+33=45