3x+y=7
9x-4y=-7
---
y=7-3x
9x-4y=-7
---
y=7-3x
9x-4(7-3x)=-7
----
y=7-3x
9x-28+12x=-7
----
y=7-3x
21x=28-7
---
y=7-3x
21x=21
---
y=7-3x
x=1
---
y=7-3.1
x=1
----
y=7-3
x=1
----
y=4
x=1
------
/x,y/=/1,4/
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1 кг = 1000 г
8 кг 3 г = 8003 г
8300 г > 8003 г
1)...=18/7+(-2*4/3)=18/7-8/3=-2/21
2)...=3*1/2+(-15/4)=3/2-15/4=-9/4
2178*6=13 068
13 068/4=3 267
3 267+ 267= 3 534
10 000-3 534=6 466