COMC 2018 B Problem 4

Past Contests COMC 2018 B
1

Determine the number of 5-tuples of integers \left(x_{1}, x_{2}, x_{3}, x_{4}, x_{5}\right) such that

  1. x_{i} \geq i for 1 \leq i \leq 5;
  2. \sum_{i=1}^{5} x_{i}=25.