For the first part we want to know how much the newspaper costs. Listening to the entire dialogue, the second customer asks for a newspaper (しんぶん). The shopkeeper then asks for 80 yen (八十円).

しんぶんは80円です。

しんぶんは80円です。

It costs 80 yen.

For the second part we want to know how much the umbrella costs. Listening to the entire dialogue, the third customer asks about the price of the umbrella (かさ). The shopkeeper then informs that it is 1000 yen (千円).

かさは1000円です。

かさは1000円です。

It costs 1000 yen.

In the third part, we want to know how much the chocolate costs. After listening to the entire dialogue, none of the customers asked for chocolate. So, we have to put a question mark ?

For the fourth part, we want to know how much the cola costs. The second person goes back to shopkeeper and asks for a cola. Listening to the entire dialogue (towards the end), the shopkeeper asks for 120 yen (百二十円) for the cola.

コーラは１２０円です。

コーラは１２０円です。

It costs 120 yen.

For the fifth part, we want to know how much the gum costs. The first person asks for gum. Listening to the entire dialogue (towards the beginning), the shopkeeper asks for 100 yen (百円) for the gum.

ガムは１００円です。

ガムは１００円です。

It costs 100 yen.