A business sells goods which have a list price of £800. The following discounts are avaliable to the buyer:
20% trade discount
5% settlement (cash) discount for settlement within 14 days
(a) The sales invoice should show a VAT amount (at 20%) of
<1>£121.60 <2>£128.00 <3>£160.00
(b) The total price for the goods on the invoice should be:
<1>£729.60 <2>£761.60 <3>£960.00
请教运算步骤, 多谢!!