Roberto is raising chickens for eggs. He buys 4 chickens for $20 each. They cost $1 in total a week to feed and each produces 3 eggs a week that will last forever. He used to buy 1 dozen eggs a week and spent $2 per dozen. After how many weeks will the chickens be cheaper than buying his eggs?
The chickens cost $80 because 4 x 20 = <<4*20=80>>80
His chickens produce a dozen eggs a week because 4 x 3 = <<4*3=12>>12
Each week that he has chickens is $1 cheaper than buying eggs because 2 - 1 = <<2-1=1>>1
After 80 weeks his chickens will be paid off because 80 / 1 = <<80/1=80>>80
After 81 weeks the chickens will be cheaper than buying eggs because 80 + 1 = <<80+1=81>>81
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Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
You are solving math problems. Here are some examples of how to solve the task:

The region east of plain A is 50 square miles less than the region east of plain B. If plain B has 200 square miles, how many square miles do the plains have in total?The region of plain A has a total of 200 - 50 = <<200-50=150>>150 square miles.
The total number of square miles for both plains is 150 square miles for plain A + 200 square miles for plain B = <<150+200=350>>350 square miles
#### 350[END]

Vinnie is writing an essay and needs to make sure that he has not exceeded the 1000-word limit. He wrote 450 words on Saturday and 650 words on Sunday. How many words has Vinnie exceeded the limit by?Vinnie has written a total of 450 words on Saturday + 650 words on Sunday = <<450+650=1100>>1100 words.
He has therefore exceeded the limit by 1100 written words – 1000 word limit = <<1100-1000=100>>100 words.
#### 100[END]

Now, solve this next question in the style of the above examples:

Roberto is raising chickens for eggs. He buys 4 chickens for $20 each. They cost $1 in total a week to feed and each produces 3 eggs a week that will last forever. He used to buy 1 dozen eggs a week and spent $2 per dozen. After how many weeks will the chickens be cheaper than buying his eggs?

### Response:
The chickens cost $80 because 4 x 20 = <<4*20=80>>80
His chickens produce a dozen eggs a week because 4 x 3 = <<4*3=12>>12
Each week that he has chickens is $1 cheaper than buying eggs because 2 - 1 = <<2-1=1>>1
After 80 weeks his chickens will be paid off because 80 / 1 = <<80/1=80>>80
After 81 weeks the chickens will be cheaper than buying eggs because 80 + 1 = <<80+1=81>>81
#### 81