Решите пожалуйста 20 баллов

2a+3b-a+8b+7a=2a-a+7a+3b+8b=8a+11b

a-2b+3b+6a=7a+b

2(k-a)-(k-a)=(k-a)(2-1)=k-a

(ab+1)-(ab+1)=0  (...=ab+1-ab-1=0)

0.6(3x-1)-(2.4x-2)+2x=1.8x-0.6-2.4x+2+2x=1.4x+1.4=1.4(x+1)

0.3(3x-2)-(2.1x-2)+3x=0.9x-0.6-2.1x+2+3x=1.8x+1.4

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12-(5-9)=16

12-5+9=16

16=16

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4b-5b+6b=5b

-b+6b=5b

5b=5b

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4a-2a+a=3a

2a+a=3a

3a=3a

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5a-2=a+(4a-2)

5a-2=a+4a-2

5a-2=5a-2       ( 0=0 )

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3b+5-(b-1)=3b+5-(b-1)

3b+5-b+1=3b+5-b+1

2b+6=2b+6

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10a-(6a-9b)=4a+9b

10a-6a+9b=4a+9b

4a+9b=4a+9b

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(0.7n-0.6m)-2(0.4n-0.3m)= - 0.1n

0.7n-0.6m-0.8n+0.6m= - 0.1n

-0.1n= -0.1n

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12a-4(3a-7b)=(4a+b)-(4a-27b)

12a-12a+28b=4a+b-4a+27b

28b=28b

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4.9a-4(a-0.6b)=0.3(3a+8b)

4.9a-4a+2.4b=0.9a+2.4b

0.9a+2.4b=0.9a+2.4b