IPMAT Indore (SA) PYQs

The total number of positive integer solutions of $21 ≤ a + b + c ≤ 25$ is

The number of solutions of the equation $x_1 + x_2 + x_3 + x_4 = 50$, where $x_1, x_2, x_3, x_4$ are integers with $x_1 \geq 1, x_2 \geq 2, x_3 \geq 0, x_4 \geq 0$ is

The number of 5-digit numbers consisting of distinct digits that can be formed such that only odd digits occur at odd places is