Answer:
More than 390 , less than 780 pigs per 195 cows
Step-by-step explanation:
Cows Pigs Trade off Ratio (Cows:Pigs)
Rob 10 20 1:2
Big 9 36 1:4
Rob can produce 1 cow by less opportunity cost i.e sacrifising less pigs than Big (2 < 4). Big is 4X productive in Pigs than cows, but Rob is lesser i.e 2X productive in Pigs than cows
So: Rob has comparative advantage in Cow, Big has comparative advantage in Pigs. Complete specialisation means Rob will raise only Cows & Big will raise only Pigs. Rob will sell Cow to Big, Big pigs to Rob.
Monthly Production Capacity with full specialisation [Given]
Cows Pigs
Rob 300 0
Big 0 1080
Trade will be beneficial for both if they both get better than domestic terms of trade : Rob gets more than 2 (20/10) pig per cow. Big gets more than 0.25 (9/36) cow per pig or 4 pigs per cow. So, for 195 cows - Big would send Rob more than 390 (2x195) pigs & less than 780 (4x195) pigs