Come up with a question and reasoning that would justify this answer: 19
Question and rationale: The question is: A 40-bead necklace is made up of three kinds of beads. There are seven amethyst beads and twice as many amber beads as amethysts. The third beads are turquoise. How many turquoise beads are in the necklace?
Step-by-step reasoning process: There are 7 * 2 = 14 amber beads. Thus, there are 40 - 7 - 14 = 19 turquoise beads in the necklace.

Come up with a question and reasoning that would justify this answer: 12
Question and rationale: The question is: Ivan has a piggy bank that can hold 100 pennies and 50 dimes. How much, in dollars, does Ivan have if he has filled his two piggy banks with those coins?
Step-by-step reasoning process: Ivan has 50 x 10 = 500 cents from the 50 dimes in his one piggy bank. So, he has a total of 100 + 500 = 600 cents in one of his piggy banks. Since 100 cents is equal to 1 dollar, then Ivan has 600 / 100 = 6 dollars from one of his piggy banks. Therefore, Ivan has a total of $6 x 2 piggy banks = $12 from his two piggy banks.

Come up with a question and reasoning that would justify this answer: 90
Question and rationale: The question is: Eric decides to go to the park. He runs for 20 minutes, then jogs for 10 minutes to reach the park. When he returns, he takes a different route home and this takes him 3 times as long as his trip there. How long does it take Eric to return home?
Step-by-step reasoning process: Eric's trip to the park took 20 minutes running + 10 minutes jogging = 30 minutes. So his return trip took 30 minutes * 3 = 90 minutes.

Come up with a question and reasoning that would justify this answer: 30
Question and rationale:
The question is: In a block of flats, there are 120 apartments. 85% of them have at least 1 resident, while 60% of the apartments have at least two residents. How many apartments have only one resident?
Step-by-step reasoning process: At least one person lives in 85 / 100 * 120 = 102 apartments. At least two persons live in 60 / 100 * 120 = 72 apartments. So in every of the 102 - 72 = 30 apartments, only one person is living.