Posted by **Ashly** on Friday, August 20, 2010 at 6:00pm.

Solve by the elimination method:

7r-9s=-35

9r+7s=85

- Algebra -
**Judy**, Friday, August 20, 2010 at 6:27pm
(7r-9s)7=(-35) 7

(9r+7s)9=85.9

7(7r-9s)=765

7(7r-9s)=-35.7

9(9r+9s)=765

7(7r-9s)=-245

9.9r+9.7s=765

7.7r-7.9s=-245

81r+63s=765

49r-63s=-245

81r+63s=765

49r-63s=-245

(81r+63s)+(49r-63s)=765.245

49r-63s=-245

1230r=520

49r-63s=-245

130r/130=520/130

49r-63s=-245

r=2^3-1

49r-63s=-245

r=4

49.4-63s=-245

196-63s=-441

63s/63=441/63

s=7^2-1

s=7

- Algebra -
**Jen**, Friday, August 20, 2010 at 11:15pm
No, no, no, no, no, no, no...I have no idea what all that nonsense above is.

7r-9s=-35

9r+7s=85

Multiply the first equation by 7 and the bottom by 9 so that the s's cancel.

49r-63s=-245

81r+63s= 765

130r=520

r=4

Now put r=4 back into any original equation.

9(4)+7s=85

36+7s=85

7s=49

s=7

(4,7)

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