Question

HELP WITH LINEAR EQUATIONS!!
will fan and medal :)

Answer 1

You just purchased a cellular phone and are trying to determine to which cell phone company you will give your business. When you contacted the Talks-A-Lot Company, they were offering a monthly plan of $40 for 600 minutes and $0.35 for each minute exceeding the 600 minutes. In the Sunday paper you see an ad for the Chat-Away Company, which offers a monthly plan of $50 for 600 minutes and $0.10 for each minute exceeding the 600 minutes. How many minutes would you have to talk over and above the 600 minutes for the cost to be the same with both companies? What would be the equal cost?


Set up a linear system consisting of two equations. Assume you will talk for a minimum of 600 minutes. The first equation would be for the Talks-A-Lot Company. The total cost, y, equals the base fee plus cost per minute times the number of minutes exceeding 600 minutes. The second equation would be set up just like the first, only you need to use the information for the Chat-Away Company.

Answer 2

I would recommend you try to get all your figures, and company names in one place to begin.

Eg.

Talk A-lot > $40, 600mins + $0.35/min exceeding 600 mins.

Answer 3

ok one sec

Answer 4

It's also worth noting, there is more than one way to solve this.

@ganeshie8 feel free to correct me.

Answer 5

wait a quick question... why did you write a > sign?

Answer 6

I apologise, it's just a symbol I used to dictate ''associated info''

Answer 7

Not greater than, it might aswell have been ->

Answer 8

ok thanks
so is this good?

Talk A-lot = $40, 600mins + $0.35/min exceeding 600 min
Chat away = $50, 600mins + $0.10/min exceeding 600 mins.

Answer 9

Yeah, that's good. We always try to take the ''wordiness'' out of the question!

So, any idea where you'd go next?

Answer 10

" The total cost, y, equals the base fee plus cost per minute times the number of minutes exceeding 600 minutes. " this is what it says in the 2nd one, so y=40+0.10x for the first one?

Answer 11

and is the other one going to be y=50+0.10x?

Answer 12

Just a moment, OpenStudy is being slow for me :)

Answer 13

its ok!

Answer 14

My question was, what type of mathematical solution are you familiar with? Have you done matrics, substitution?

Answer 15

I don't know what matrics is... but I am learning the substitution method.

Answer 16

Ah! Ok, then I will try to guide you to the answer, rather than just give you the solution OK? :)

Answer 17

sounds good!

Answer 18

y=40+0.10x
y=50+0.10x

Were your answers?

Answer 19

yup. I think?

Answer 20

Well firstly, y=40+0.10x? Can you see the mistake with the x value? :)

Answer 21

oh, y=40+0.35x correct?

Answer 22

Yes, but we are also forgetting something, in the equation, can you guess what it is?

Answer 23

?

Answer 24

Our 600 minutes! :)

Answer 25

what do you do with the 600 min? I thought bc you're assuming its over the 600 and the 40 was covering the first 600 I think..

Answer 26

it says to assume its over 600 min when writing the equation

Answer 27

It says ''assume you will talk for a minimum of 600 minutes.'' Yeah?

Answer 28

so where would the 600 go in the equation if its like, in the past?

Answer 29

How about (x-600) ?

Answer 30

ok... so
y=40+0.35(x-600)
y=50+0.10(x-600)

Answer 31

I think that is the right way to go.

Do you understand to this point?

Answer 32

yes. Thank you so much

Answer 33

Ok, so we have two equations, both linear as the Q states.

Since both equations are Y, we can set them equal to each other, make sense?

Answer 34

no

Answer 35

wait like solve the system of equations?

Answer 36

Ok.

So:

y=40+0.35(x-600)
y=50+0.10(x-600)

We have two unknowns, X & Y.

Since both equations are Y.

We can set 40+0.35(x-600) = 50+0.10(x-600)

Answer 37

Now we've only got 1 unknown :)

Answer 38

oh, ok.

Answer 39

So, do you know what to do next?

Answer 40

solve for x.

Answer 41

Try it :)

Answer 42

40+0.35(x-600) = 50+0.10(x-600)
+600 +600
_______________________________
40+0.35x = 50+0.10x
??????????????????

Answer 43

40+0.35(x-600)=50+0.10(x-600)
40+0.35x-210=50+0.10x-60

Answer 44

what?

Answer 45

Multiply out the brackets first.

Answer 46

how?

Answer 47

40+0.35(x-600)=50+0.10(x-600)

0.35(x-600) = 0.35x - 210 :)

Answer 48

Eg.

Answer 49

where does the 210 come from.

Answer 50

0.35 x 600

Do you know how to multiply brackets?

Answer 51

no

Answer 52

sorry to say this, but I only have like 3 minutes before I have to leave. I think I'll just meet with my teacher or review the lesson. I've really apreciated your help @Asylum15

Answer 53

If you don't know how to multiply out brackets, I suggest you mend that.

Let me know how you get on.

You solve for X, and substitute the X value back into one of the equations, to solve for Y.

Answer 54

thanks again @Asylum15