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April 20, 2014

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Posted by **Theresa** on Friday, September 7, 2012 at 3:18pm.

7a + 6b = 3

-7a +b = 25

The solution of the system is?

- Algebra....HELP!! -
**Adam F**, Friday, September 7, 2012 at 3:33pm7a + 6b = 3

-7a + b = 25

b = 7a + 25

Solve for a

7a + 6(7a + 25) = 3

7a + 42a + 150 = 3

49a + 150 = 3

49a = -147

a = -3

Solve for b

-7(-3) + b = 25

21 + b = 25

b = 4

Check answers

7a + 6b = 3

7(-3) + 6(4) = 3

-21 + 24 = 3

-7a + b = 25

-7(-3) + 4 = 25

-21 + 4 = 25

Answers:

a = -3

b = 4

- Algebra....HELP!! -
**Bosnian**, Friday, September 7, 2012 at 3:48pm7 a + 6 b = 3

+

-7 a + b = 25

________________

7 a + ( - 7 a ) + 6 b + b = 3 + 25

7 b = 28 Divide both sides by 7

7 b / 7 = 28 / 7

b = 4

7 a + 6 b = 3

7 a + 6 * 4 = 3

7 a + 24 = 3 Subtract 24 to both sides

7 a + 24 - 24 = 3 - 24

7 a = - 21 Divide both sides by 7

7 a / 7 = - 21 / 7

a = - 3

Proof :

-7 a + b = 25

- 7 * ( - 3 ) + 4 = 25

21 + 4 = 25

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