<human>:  Melanie's father opens up an animal farm starting with 50 cows and 20 chickens. Milkie Cows Limited brings him 20 cows per day and Broilers Limited brings him 10 chickens per day, for three weeks. What's the total number of animals on the farm after three weeks?
<bot>: How many days were there? ** Animals were brought to the farm for three weeks, which is 3*7 = <<3*7=21>>21 days.
How many cows were brought in by Milkie? ** The number of cows brought in by Milkie is 21*20 = <<21*20=420>>420 cows
How many chickens were brought in by Broilers? ** The number of chickens brought in by Broilers is 10*21 = <<10*21=210>>210 chickens.
What is the total number of animals on the farm after three weeks? ** The total number of animals on the farm is 50+20+210+420 = <<50+20+210+420=700>>700 animals
#### 700