{10(x+y)=30+8x
{9(x-y)=-49-8
решите

{10(x+y)=30+8x

{9(x-y)=-49-8y

{10x+10y=30+8x

{9x-9y=-49-8y

{10x-8x+10y=30

{9x-9y+8y=-49

{2x+10y=30

{9x-y=-49|*10

2x+10y=30

90x-10y=-490

2x+90x=30-490

92x=-460|:92

x=-5

10*(-5)+10y=30+8*(-5)

-50+10y=30-40

10y=-10+50=10y=40:10

4=4

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ответ:(-5;4)

Пошаговое объяснение:

10(x+y)=30+8x

9(x-y)=-49-8

10x+10y=30+8x

9x-9y= -57

2x+10y=30  

9x-9y= -57

18x+90y=270

-18x+18y=114

90y+18y=270+114

108y=384

y= 32/9

2x+10y=30  

2x+10*32/9=30

2x+320/9=30

2x=30-320/9

2x= -50/9

x=-50/9 / 2

x= -25/9

x= -2 7/9

y=3 5/9