The number of solutions to the system of equations `x_1+x_2+x_3+x_4+x_5=20` and `x_1+x_2=15` wher `x_k>=0`

Explanation

To solve the system of equations \(x_1 + x_2 + x_3 + x_4 + x_5 = 20\) and \(x_1 + x_2 = 15\) with the condition \(x_k \geq 0\), we can follow these steps:

### Step 1: Analyze the equations
We have two equations:
1. \(x_1 + x_2 + x_3 + x_4 + x_5 = 20\)
2. \(x_1 + x_2 = 15\)

From the second equation, we can express \(x_1 + x_2\) as 15.
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