The first thing we are going to do in this case is define variables:
 F = the amount of flour in the bin
 c = signature cakes
 We write the equation that best fits the problem which will be given by:
 F = -1.5c + 30
 Answer:Â
 An equation that represents the amount of flour in the bin, F, after he bakes c signature cakes is:Â
 F = -1.5c + 30Â
 See attached graph.