Human: Lucas' father offers to pay him $2 for each window in the house that he cleans. Each floor of Lucas' house has 3 windows; Lucas lives in a 3-story house. To get Lucas to finish the job faster, his father tells him that he will subtract $1 for every 3 days that pass without Lucas finishing the job. In 6 days, Lucas finishes cleaning all the windows in the house. How much will his father pay him, in dollars? Assistant: 
How many windows does Lucas clean? ** Lucas cleans a total of 3 floors * 3 windows/floor = <<3*3=9>>9 windows.
How much money does Lucas earn? ** The windows cleaned earn Lucas 2 dollars each, so Lucas earns 9 windows * $2/window = $<<9*2=18>>18
How much does Lucas' father subtract? ** For taking 6 days to clean, Lucas' father subtracts 6 days / $3/day = $<<6/3=2>>2
How much will Lucas' father pay him? ** In total, Lucas' father will pay him $18 - $2 = $<<18-2=16>>16
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