Question

Difficulty: MediumTranslating and Solving Algebraic Word Problems

An online streaming service offers a basic monthly plan that costs 1212 dollars plus 1.501.50 dollars for each premium movie rented. A premium monthly plan costs 2020 dollars and includes 33 free premium movie rentals, with each additional rental costing 1.001.00 dollar. If a subscriber rents xx premium movies in a month, where x>3x > 3, which of the following expressions represents the savings, in dollars, of the premium plan compared to the basic plan?

  1. A
    0.50x80.50x - 8
  2. B
    50.50x5 - 0.50x
  3. 0.50x50.50x - 5Answer
  4. D
    2.50x112.50x - 11
  5. E
    0.50x110.50x - 11

Answer

0.50x50.50x - 5
The cost of the basic plan for xx rentals is 12+1.50x12 + 1.50x dollars. Under the premium plan, the first 33 rentals are free, so the subscriber only pays for x3x - 3 rentals. The cost of the premium plan is 20+1.00(x3)20 + 1.00(x - 3) dollars, which simplifies to 17+x17 + x dollars. The savings of the premium plan compared to the basic plan is the difference between the basic cost and the premium cost: (12+1.50x)(17+x)=0.50x5(12 + 1.50x) - (17 + x) = 0.50x - 5 dollars.

Step-by-Step Solution

1
Write the expression for the cost of the basic monthly plan.
12+1.50x12 + 1.50x
The basic plan has a flat fee of 1212 dollars and a rate of 1.501.50 dollars per movie for all xx movies rented.
2
Write the expression for the cost of the premium monthly plan.
20+1.00(x3)20 + 1.00(x - 3), which simplifies to 17+x17 + x.
The premium plan has a flat fee of 2020 dollars. Since 33 rentals are free, the subscriber only pays 1.001.00 dollar each for the remaining x3x - 3 rentals.
3
Subtract the premium plan cost from the basic plan cost to find the savings.
(12+1.50x)(17+x)=0.50x5(12 + 1.50x) - (17 + x) = 0.50x - 5
Savings represents the difference in cost: Basic Cost minus Premium Cost.

Key Concept

Translating verbal descriptions of multi-step costs into linear algebraic expressions and simplifying them.
Estimated Time:1m 30s
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