Algebra expressions problem

Hi, I's reviewing my algebra skills for my economics program. i need some help with the following question:

Q: A good costs a basic $180 a unit but if an order is made for more than 10 units this price is reduced by a discount of $2 for every one unit increase in the size of an order (up to a maximum of 60 units purchased), i.e. if the order size is 11, price is $178, it is is 12, price is $176 etc. Write an expression for the total cost of an order in terms of order size and simplify it. Assume order size is between 10 and 60 units.

Any help would be greatly appreciated.

Thanks