Answer:
C) $40.50
Step-by-step explanation:
It is given to you that 20 articles cost $90. Find the unit cost of the articles. Divide the total cost of the articles with the amount of articles there are:
$90/(20 articles) = $4.50/article.
Each article costs $4.50 each.
Next, find the cost of 9 articles. Multiply the total amount of articles with the unit cost:
4.50 x 9 = 40.50
C) $40.50 is your answer.
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