A service station sells bottles of water for $2 each.

It also has a special of 3 bottles for $5.

What is the lowest cost of 8 bottles of water?

A pet store sells its high growth dog food in four different sizes.
 

 
What is the lowest price a customer can pay for 10 kg of high growth dog food?

This table shows the prices of different kinds of nuts sold at a farmers' market.

Which one of these are the most expensive nuts per kilogram?

Nigella needs to buy some olive oil.

The supermarket sells Nigella's favourite oil in a number of different sizes.

Which size costs her the least per mL?