FM 8.0v3 calculated result with parameters
I'm using FM pro 8.0v3 on Mac OS10.4.11. I have a data base with fields for height, width, sq-inch, and cost per sq-inch. The sq-in. field is a calculation of height x width. I would like to set up the cost per sq-in. field with parameters, where if the sq-in result is say between 100 and 200 the cost is 300, if the sq-in. result is between 201 and 600 the cost is 575, and so on. Any help with the formula would be appreciated.