Question

How do I solve the following equations using the substitution method? 20x-5y=20 and y=4x+4

Answer 1

20x-5y=20
y=4x+4

The second equation gives you a value for y 'in terms of x'

so 'substitute' 4x+4 in th eFIRST equation wherever there is a y
This will give you a new equation with only x in it

Write that equation here.....

Answer 2

20(4x+4)-5y=20

Answer 3

NO - you must substitute wherever you saw a y, not an x

Answer 4

20x-5(4x+4)=20

Answer 5

That's right - now expand the bracket, and collect the x terms together

Answer 6

20x-20x+20=20

Answer 7

hmmm - I see a problem

Answer 8

they cross each other out?

Answer 9

You have not expanded the bracket properly

Answer 10

I am not understanding. I took the y and replaced it with the 4x+4 then multiplied by the 5 from the 5y?

Answer 11

20x-5y=20
y=4x+4

If you rearrange the first
5y=20x-20

If you multiply the second by 5
5y = 20x +20

These equations cannot both be true - I think there is an error in your question....

Answer 12

So there is no solution?

Answer 13

They are parallel lines, therefore do not have a solution.

Have you typed the question properly?

Answer 14

yes I confirmed the question is correct but one of the options on my assignment is that there is no solution or that there is infinitely many solutions