Give the step-by-step reasoning process and then the final answer. Enrico owns a rooster farm, he sells each rooster for $0.50 per kilogram. He was able to sell a 30-kilogram rooster and a 40-kilogram rooster, how much money was he able to earn?
Enrico was able to sell the 30 - kilogram rooster for 30 x 0.50 = $15. And he was able to sell the 40 - kilogram rooster for 40 x 0.50 = $20. Therefore, he was able to earn $20 + $15 = $35.
The final answer: 35.