Given a-2b=8, 4a+3b= 21; prove b= -1

please give a step by step answer

Step-by-step explanation:

We can solve this with some pretty simple substitution

First write that a=2b+8

and our reasoning for this is that we added 2b from the first equation

Then write

4(2b+8)+3b=21

After we figured out what A was in the previous part we are able to substitute that into our other equation

Then you solve for b from here

8b+32+3b=21

11b=-11

b= -1

If you have any questions leave them below

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step-by-step explanation:

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