Basicly, A win everything that B,C,D have, which = 60,000 (excluding his own chips)
If D wins, he wins all he has = 10,000 * 4 players (including his own chips). The left over is sidepot, that's bascily means that at the paraticular point u can forgot the existence of D, any of the remaining (B,C,D) still in the game, splitting the pot , e.g if A wins the side pot, = total - what D won. if B wins .. ,... same rules apply.
Is not that hard to caculate in that situation, but take a bit more time, and to be honest, so unlikely will come to this situation..
