Substitution and find plots

Algebra
Tutor: None Selected Time limit: 1 Day

I think I am way off :

x+y=18

4x+5y=3

x=18-7y

4x(18-7y)+5y

72-28y+5y=3

Sep 11th, 2015

Thank you for the opportunity to help you with your question!

to substitute given equations you express one value in terms of the other eg x in terms of y and the use it in the other equation

eg

x+y=18

4x+5y=3

x=18-y

4(18-7y)+5y=3

72-28y+5y=3

Move the ys to the other side

72-3=28y-5y

69=23y

y=69/23

y=3


so x=18-3

x=15

Please let me know if you need any clarification. I'm always happy to answer your questions.
Sep 11th, 2015

What would be the plots?

Sep 11th, 2015

you can draw the line which passes through

15,3 then you plug in values like the value of x when y is 0 for both equations and the value of y when x =0

The lines should cross one another at 15,3.


You can take any values on x which are near 15 then plug them in the equation of each line and plot..

Sep 11th, 2015

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Sep 11th, 2015
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Sep 11th, 2015
Dec 10th, 2016
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