Question: Santino has 2 papaya trees and 3 mango trees. If each papaya tree produces 10 papayas and each mango tree produces 20 mangos, how many fruits does Santino have in total?
How to solve this?
Answer: 
Santino has 2 * 10 = 20 papaya fruits
Santino has 3 * 20 = 60 mango fruits
In total, Santino has 20 + 60 = 80 fruits