Question: 40% of the mosquitos in Jack's area are infected with malaria. 20% of the mosquitos are infected with Zika virus. Without a vaccine, the chances of getting infected with either virus after getting bitten by an infected mosquito are 50%. Jack is taking an experimental malaria vaccine that reduces the chances of getting infected after getting bitten by 50%. If Jack gets bitten by a random mosquito, what is the percentage chance he catches either Zika virus or malaria?
Answer: First find Jack's chances of getting bitten by an infected mosquito: 40% + 20% = 60%. The chance of being infected by a mosquito with after being bitten: 60% * 50% = 30%. Then find the chances of getting ill after receiving the vaccine: 30% * 50% = 15%. The answer is 15.

Question: Tyler has 21 CDs. He gives away a third of his CDs to his friend. Then he goes to the music store and buys 8 brand new CDs. How many CDs does Tyler have now?
Answer: Tyler gives away 21 / 3 = 7 CDs. After giving away a third of his CDs, Tyler has 21 - 7 = 14 CDs. After buying new CDs, Tyler has 14 + 8 = 22 CDs. The answer is 22.

Question: Daria wants to go to a concert by her favorite band. She wants to buy tickets for her and for three of her friends. One ticket cost is $90. How much money does Daria need to earn if she currently has only $189?
Answer: Daria wants to buy tickets for four persons, so the cost will be 4 tickets * $90 / ticket = $360. Daria currently has $189, so she needs $360 - $189 = $171 more. The answer is 171.

Question: Mr. Sergio is a fruit grower producing apples, mangoes and oranges. In a particular season, the total produce of apples was twice the total produce of mangoes, and the total produce of oranges was 200 kg more than that of mangoes. If his farm produced 400 kg of mangoes and he sold the fruits at $50 per kg, calculate the total amount of money he got in that season.
Answer:
If the total production of mangoes was 400, then orange production was 400 + 200 = 600 kg of oranges. Since apple production was twice the total production of mangoes, Mr. Sergio had 2 * 400 = 800 kg of apples. The total quantity of fruits produced at Mr. Sergio's farm is 800 kg of apples + 600 kg of oranges + 400 kg of mangoes = 1800 kg of fruits. If Mr. Sergio sold the fruits at $50 per kg, his total income from the sales is 1800 * $50 = $90000. The answer is 90000.