There are three piles of identical red, blue and green balls and each pile contains at least 10 balls. The number of ways of selecting 10 balls if twice as many red balls as green balls are to be selected, is

Options

A. 3
B. 4
C. 6
D. 8

Explanation

To solve the problem step by step, we start by defining the variables based on the given conditions.

### Step 1: Define Variables
Let:
- \( x \) = number of green balls selected
- \( 2x \) = number of red balls selected (since we need twice as many red balls as green)
- \( z \) = number of blue balls selected

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