Annette C.

Writing expressions

The average # of tea drinkers in the year 2000 was 12.5 million and the average # of coffee drinkers was 16 million.  During the next 3 years, the # of tea drinkers would increase an average of 5 million per year and the number of coffee drinkers would decrease an average of 2 million per year.  Write an expression describing the relationship between the # of tea drinkers and time (x years after 2000), and an expression describing the # of coffee drinkers and time.

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4.9 (52)

Math Tutor - Patient and Experienced

Mykola V.

I'm pretty sure it would be best to show the student how you arrived at 2T+5C instead of just stating it. A better approach would be to solve for x in terms of either T or C and then plug it in to the other expression, at least it would be easier for the student to understand that.
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11/20/12

Roman C.

tutor

Yes. I just used the least common multiple of the coefficients of x terms, which is 10. Multiplying T(x) by 2 make's it's x-coefficient 10, and multiplying C(x) by 5 makes it's x-coefficient -10. Now adding the resulting equations makes the x-terms cancel.

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11/20/12

Mykola V.

Thank you. =]

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11/20/12

Tutor
4.6 (13)

Certified High School AP Calculus and Physics Teacher

Roman C.

tutor
You have a typo. Should be 16 - 2x for coffee.
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11/20/12

Robert J.

Thank you!

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11/20/12

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