In the first round, Andy has -320 times 1/2, which corresponds to
[tex]-320\times\frac{1}{2}=-\frac{320}{2}=-160[/tex]In the second round, Ansy has
[tex]710\times\frac{1}{4}=\frac{710}{4}=\frac{355}{2}[/tex]which corresponds to 177.5 (in decimals).
Finally, Andy's final point is
[tex]-320\times\frac{1}{2}+710\times\frac{1}{4}-500[/tex]which is equal to
[tex]-160+177.5-500=-482.5[/tex]that is, Andy's final point is - 482.5.