请教grounping payroll tax问题

dan

因为missed了payroll tax这堂课，在grouping payroll tax问题上got stuck in.请教高手以下问题。

Company X, Y & Zare grouped for payroll tax. They employ only in WA and had the following taxable wages in October 2012:
Company X: $77,000
Company Y: $15,000
Company Z: $9,000
Calculate the payroll tax payable by each company in October 2012.

我知道Company X作为NGE，so Company X is entitled to threshold amount $62,500, and its payroll tax payable is ($77,000-$62,500)*5.5%.
但我不知道在这种情况下，company Y和Company Z的payroll tax payable 怎么计算？即pro-rata的公式该如何？

请教高手。谢谢！！！！

dan

Good on Loopmoon!!!!!

Thx I've passed my assessment :-)