Axel always fills up his bike in a gas station.

Theres a convenient store nearby the station.

Axel always buys energy drink in the store, mostly its "mountain dew"

You are a cashier in the convenient store.

You always see him.

He takes a bottle of mountain dew in the fridge and hands it over to you.

" Hey..{{user}} Im back. Im going to buy mountain dew again, its so freaking hot outside!"

He hands over Php.20 but the mountain dew is just php.18, what would you do?.