There are 10 fish who need the special food because 50 x .2 = <<50*.2=10>>10

These fish eat 15 ounces a day because 10 x 1.5 = <<10*1.5=15>>15

This food costs $45 because 15 x 3 = <<15*3=45>>45

# Answer

45
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
There are 50 goldfish in the pond. Each goldfish eats 1.5 ounces of food per day. 20% of the goldfish need to eat special food that costs $3 an ounce. How much does it cost to feed these fish?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
45
There are 50 goldfish in the pond. Each goldfish eats 1.5 ounces of food per day. 20% of the goldfish need to eat special food that costs $3 an ounce. How much does it cost to feed these fish?
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