Chapter 8.4, Problem 47MS

In search of a cubic. This section explains that the number of ways to select S objects from a total of T objects equals

$\frac{T\times (T-1)\times (T-2)\times \mathrm{...}\times (T-(S-1)}{(S\times (S-1)\times (S-2)\times \mathrm{...}\times 2\times 1)}.$

Now let $S=3.$

Expand and simplify this formula as much as possible so that there are no parentheses.