2題數學題.........

1
2-y=9
-y=9-2
-y=7
y=-7

2
-n分9唔知係咩...做2條你睇
______________________________
-n
__=3
9

-n=3x9

n=-27

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9
__=3
-n

9=3x(-n)

9
__=-n
3

-3=n

1.2-y=9
-y=9-2
-y=7
y=-7

2.n/9=3
n/9*9=3*9
n=27

1.-11
2.27