Posted by **SAP** on Thursday, September 30, 2010 at 8:02pm.

Solve by elimination method. Please show step by step process.

7r-4s=-7

4r+7s=61

- Math need by 9pm cst -
**bobpursley**, Thursday, September 30, 2010 at 8:05pm
multiply the top equation by 7, and the bottome equation by 4.

Then add the equations, which will eliminate the s variable.

I will be happy to critique your work

- Math need by 9pm cst -
**SAP**, Thursday, September 30, 2010 at 9:11pm
7r-4s=-7 (7)

4r+7s=61 (4)

49r - 28s = -49

16r + 28s = 244

---------------

65r = 195

195/65 = 3 (simplified) (3, is the first number of the ordered pair.)

Now this is the part that I get lost on. I know I am suppose to substitute 3 into one of the equations above, but how do I determine which one. So if I substitute 3 into the 1st equation:

7(3)-4s= -7

21 - 4s= -7

------------

21 = -7 would my answer be -7/21

Substitute 3 into the 2nd equation:

4(3)+7s = 61

12 + 7s = 61

-------------

12 = 61 would my answer be 61/12

(3, is the first number of the ordered pair.)

(3,-7/21) or (3,61/12) which ordered pair is correct?

## Answer This Question

## Related Questions

- Math need by 9pm cst - Solve by substitution method. Show step by step process. ...
- Math need by 9pm cst - Solve. Please show step by step process. 5/8 x+1/16 x=11/...
- Algebra - How do I solve for the elimination method: 5x + 3y= -7 and 7x - 2y =13...
- math - Please solve the system with the elimination method. Explain each step as...
- Algebra 2 - I need step by step on how to solve this problem plz help I've been ...
- math - solve by the elimination method: 9x-9y=18 7y-3x=-8 please solve step by ...
- algebra - Solve by the elimination method. x+4y=45 -x+4y=27 please step by step
- Algebra 1--Step-by-Step - Can someone show me how to solve these step-by-step? ...
- Math - Solve by elimination: 5x+7y=77 , 5x+3y=53 can you please help me out step...
- alg2 check? - solve: 2x+2(x+3)=2(x+7) what I got was x=4 but I really think I ...

More Related Questions