看一本140页的故事书，已经看了全书总页数的 $\frac{4}{7}$ ，还有多少页没有看？

A: Hi, Jack. Our speech competition about sports is coming.

B: Yean. I'm ready for it. ____?

A: I have no idea about it. Could you give me some good advice?

B: Well, that depends on your hobby. What's your favorite sport?

A: ____ .

B: Then, you should collect some information about football.

A: ____？

B: You can collect the information by reading newspapers and magazines. And you can also talk about the World Cup in Russia these days.

A: ____.Thank you very much.

B: ____.Bye.

A: Bye-bye.

小明的父亲领取了3000元工资后，在商店里购买一件打折商品，原标价为人民币100元，实际支付80元。在这里，3000元、100元、80元分别执行的职能是（   ）