# Math

posted by .

Can someone help me solve the following problems using the substituion method? I need to find the ordered pairs and I do not get it.... Here they are

1)
6m+n=47
m-4n=12

2)
6x+4y=-10
-7x+y=57

3)
5x+7y=43
-4x+y=25

• Math -

I use substitution when I notice that in one of the equations one of the variables has a coefficient of 1
Then solve for that single variable
e.g. in #2
-7x + y = 57 ,
y = 7x + 57

now sub that into the other equation
6x + 4y = -10
6x + 4(7x+57) = 10
6x + 28x + 225 = 10
34x = - 218
x = -218/34 = - 109/17
then y = 7(-109/17) + 57
y = 206/17

do the other two the same way

• Math -

Okay but the homework is saying the answer is (-7,8) so how would they have gotten that from the equation you did above?

• Math -

I made a transcript error.

After 6x + 4(7x+57) = 10 it should have been
6x + 28x + 228 = -10

I had 2 errors in copying that line, sorry about that
Now i works out

• Math -

Okay so what about number one it is a + and the a - for the second problem how do you figure a subtitution problem like that? do the signs make a difference?

• Math -

For number 3 I got (6.7,51.8) is this correct?

## Similar Questions

1. ### Algebra

3x - 2y = 6 , 2x + 3= 6 are perpendicular lines but i need 3 ordered pairs for each. I used the m= y2-y1/x2-x1 method to establish that the slopes = -1. Any suggestions for ordered pairs for each line is much appreciated.
2. ### Geometry

So are these the correct ordered pairs to the problems. Our teacher told us to find ordered pairs. 1. TX=2x+1,XW=x+7;TW 2. WX=x+5,TW=4x+5:TX 1. (1,8) 2. (3,17)
3. ### 8th grande transition algebra

well, i am doing a math crossword puzzle on linear equations. I really need some help. here are the questions: what is Ax+By+C called?
4. ### College Math II

Solve by any method. a^4 – 5a^2 + 4 = 0 I am having problems figuring out what method to use to solve this problem. I need to show my steps and I am not sure how to do this. Can someone help?
5. ### Algebra

I have a few problems I need you to take a look at and tell me if I arrived at the right answer. 1. I am to use the intercepts to graph the equation x+3y=6 I used the formula y=mx+b using 3 and -6 for x I got these as my ordered pairs …
6. ### Algebra/math

I have a few problems I need you to take a look at and tell me if I arrived at the right answer. 1. I am to use the intercepts to graph the equation x+3y=6 I used the formula y=mx+b using 3 and -6 for x I got these as my ordered pairs …
7. ### algebra

I have a few problems I need you to take a look at and tell me if I arrived at the right answer. 1. I am to use the intercepts to graph the equation x+3y=6 I used the formula y=mx+b using 3 and -6 for x I got these as my ordered pairs …
8. ### Math/Check

I have a few problems I need you to take a look at and tell me if I arrived at the right answer. 1. I am to use the intercepts to graph the equation x+3y=6 I used the formula y=mx+b using 3 and -6 for x I got these as my ordered pairs …
9. ### Algebra/no response yesterday

I have a few problems I need you to take a look at and tell me if I arrived at the right answer. 1. I am to use the intercepts to graph the equation x+3y=6 I used the formula y=mx+b using 3 and -6 for x I got these as my ordered pairs …
10. ### math

solve using the substitution method....(solutions must be in ordered pairs form) 9m+n=24 m-8n=27

More Similar Questions