Question

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.

Solve the linear system using the substitution method. Please make sure to solve for both x and y.

Answer 1

OK. if y is cost and x is minutes, you can represent that by:
y=40 + .35(x-600)
y=50+10(x-600)
(assuming you're solving for the point at which they cost the same, x>600 because if x<600 they're clearly not the same price)
Multiply that out and solve.

Answer 2

ooo i have been doing this wrong.
i wrote y =600 + .35

Answer 3

You need to include the x. Otherwise, you've got this.

Answer 4

y = 40 + .35x - 210
y - 50 + .10x - 60

?

Answer 5

Answer:
y=0.35x+40
y=0.10x+50
36 minutes
They r equal at 54$
Talks a lot would b better 4 1000

Answer 6

@rouge lol thanks. but i need to show my work. && i Have no idea how to do the substitution method

Answer 7

x>600
TalkALot:
f(x)=40+0.35(x-600)
ChatAway:
f(x)=50+0.1(x-600)

point of equality:
40+0.35(x-600)=50+0.1(x-600)
0.25(x-600)=10
x-600=40
x=640

y=50+0.1(640-600)=50+4=54
or
y=40+0.35(640-600)=40+14=54

you should hire the second company (ChatAway)
f(1000)=40+0.35*400 = 180
f(1000)=50+0.1*400 = 90