@Mathematics- solve the system by substitution.
3x+7y=36
5x-7=-108
What is the solution of the system?

Question

turingtest · Answer

are we missing a "y" in the second equation?

anonymous · Answer

ya. sorry

saifoo.khan · Answer

x = -12
y = 48/7

turingtest · Answer

so is it
3x+7y=36
5x-7y=-108
??????

saifoo.khan · Answer

$$\checkmark$$

anonymous · Answer

yes

anonymous · Answer

can you guys give the work

turingtest · Answer

3x+7y=36     (1)
5x-7y=-108  (2)

First solve one equation for y or x (it doesn't matter which)
Equation (1) gives

3x=36-7y
x=(1/3)(36-7y)=12-7y/3

substitute this expression for x into the other equation, equation (2):

5(12-7y/3)-7y=-108
60-35y/3-21y/3=-108
-56y/3=-168
y=9

substitute this value of y into our expression above for x:

x=(1/3)[36-7(9)]=12-21=-9

so we have 

x=-9, y=9

check by plugging these values into the original equations.

anonymous · Answer

oh no! you guys all have different answers!

turingtest · Answer

There was just two of us and saifoo did not see the equation as it was supposed to be (with the missing y) like I said check by plugging these values into the original equation:

3(-9)+7(9)=???     
5(-9)-7(9)=???

use your calcluator (or brain) and you will see that you get the original values:

3(-9)+7(9)=36    
5(-9)-7(9)=-108

turingtest · Answer

and why do you say that?

turingtest · Answer

@lilg132
Dude read the posts before doing a whole problem.
There was a missing "y" in the second equation. You should have solved
3x+7y=36    
5x-7y=-108
Please read others work before posting

lilg132 · Answer

kyanmommy can you rewrite the correct question please?

anonymous · Answer

@Mathematics- solve the system by substitution.
3x+7y=36
5x-7y=-108
What is the solution of the system?

anonymous · Answer

sorry guys!

turingtest · Answer

yes, that is mine
x=-9 y=9
like I said, check by plugging in

turingtest · Answer

if you plug in lilg132's answers you get
5(-20.2)-7(13.8)=197.6
so you can see it is wrong.

turingtest · Answer

sorry
5(-20.2)-7(13.8)=-197.6
is what the second equation becomes with those answers. You should have -108 as you do originally.

anonymous · Answer

okay im confused. what is the answer

turingtest · Answer

x=-9
y=9

anonymous · Answer

okay thanks. Math is not my subject and i am failing thanks for helping

turingtest · Answer

it's ok, I just wish lilg would concede that he made a mistake and not confuse you.

anonymous · Answer

lol