A bumpy week

Each move multiplies the price by a factor; undo them all with one division.

1. The $4$ moves multiply the price by $1.2$, $0.75$, $1.5$ and $0.6$.
2. Together that is $1.2\times 0.75\times 1.5\times 0.6=0.81$.
3. So the starting price is $\frac{72.9}{0.81}=90$.

Answer: $90$