How many terms of the series `20+19(1)/(3)+18(2)/(3)+"...."` must be taken to make 300?
Explain the double answer.

Explanation

To solve the problem, we need to analyze the series given:

\[ S = 20 + 19 \cdot \frac{1}{3} + 18 \cdot \frac{2}{3} + \ldots \]

### Step 1: Identify the pattern in the series
The series can be expressed in a more general form. The first term is 20, the second term is \( 19 \cdot \frac{1}{3} \), the third term is \( 18 \cdot \frac{2}{3} \), and so on.

We can observe that:
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