Use pascals triangle to multiply the binomial (x-2)^5

The coefficients for a fifth degree polynomial are 1 5 10 10 5 1. We start at the highest power of x and the lowest power of -2, and multiply each term by the appropriate coefficient from Pascal's Triangle. We get x^5 - 10x^4 + 40x^3 - 80x^2 + 80x - 32.

How many shares did he have to begin with?