1.A company has recorded the following total costs during the last four years.

Year 2015, total costs $150 for 20 units;

Year 2016, total costs $180 for 30 units;

Year 2017, total cost $100 for 14 units;

Year 2018, total costs $160 for 25 units.

The variable costs are $ per unit. (using High-low method)

2.A business regularly uses material A and currently has inventory 100 kg for which it paid $1000 last month, if this were to be sold as raw material today, it could be sold for $5 per kg. You are aware that the material can be bought on the open market for $15 per kg. A customer has made an order that will use 300 kg of the materials. The relevant cost of the 200 kg is $.

3.You make some bookmarks and sell them to your classmates. You need to spend $0.5 on the materials of one bookmark, and then pay $1 per bookmark for an artist for his drawing on the products (bookmarks). You should pay $30 to rent a drawing board for one week. The price is $3 per bookmark. You need to sell at least bookmarks during the week to avoid a loss.