Răspuns :

Rrodica228id

Răspuns:

a) 12+3a+6b=51

a+2b=?

12+3(a+2b)=51

3(a+2b)=51-12

3(a+2b)=39

a+2b=39÷3

a+2b=13

b) 4a+6b-3=11

6a+9b=?

2(2a+3b)=11+3

2(2a+3b)=14

2a+3b=14÷2

2a+3b=7 | ×3

6a+9b=21

c) 7a+9b+5=a+b+17

15a+20b=?

7a-a+9b-b= 17-5

6a+8b=12| ÷2

3a+4b=6| ×5

15a+20b=30

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