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January 28, 2015

January 28, 2015

Posted by **Gemma** on Saturday, January 24, 2009 at 11:50am.

Here's my inequality and how I solved it:

.16c + .20 < .18c +.19

I subtracted .19 from each side

.16c + .01 < .18c

I subtracted .16c from each side

.01 < .02c

I divided each side by .02.

My final answer does not make sense to me: c > .5. Half a phone call, or half a minute? I think I must have messed up somewhere, so if you see a mistake, please tell me.

Thank you!

- Algebra -
**Reiny**, Saturday, January 24, 2009 at 12:10pmYou actually have a rather silly question given to you.

You are dealing with two functions:

Cost(DEC) = 16t + 20 where t is in minutes and Cost is in cents

Cost(LCD) = 18t + 19

let's see where they intersect (are equal)

18t + 19 = 16t + 20

2t = 1

t = 1/2

so at 1/2 minute the cost would be the same, but apparently the cost would be calculated in whole minutes.

so for less than a minute (t=0)

for DEC it would cost 20 cents and for

LCS it would cost 19 cents.

for any vale of t ≥ 1, the cost for DEC would be less than the other agent.

What you did was mathematically correct, you just got yourself confused what your c stood for.

You got c > .5, I got t = .5, you solved an inequation, I solved an equation.

since our solution fell within the fixed cost rate of anything less than 1 minute , we cannot really use that result.

Hope that clears up your problem.

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