The second puzzle has 1000 * .5 = 500 more pieces than the first. So it has 1000 + 500 = 1500 total pieces. That means those two puzzles have 1500 * 2 = 3000 pieces. So in total there were 3000 + 1000 = 4000 pieces.
The answer: 4000
Reverse engineering the question: John buys 3 puzzles. The first puzzle has 1000 pieces. The second and third puzzles have the same number of pieces and each has 50% more pieces. How many total pieces are all the puzzles?

Mary took 10 + 6 = 16 chickens. John took 16 + 5 = 21 chickens. John took 21 - 10 = 11 more chickens than Ray.
The answer: 11
Reverse engineering the question: The Grey's bought several chickens at a sale. John took 5 more of the chickens than Mary took. Ray took 6 chickens less than Mary. If Ray took 10 chickens, how many more chickens did John take than Ray?

The number of musicians in the orchestra is 11 + 12 = 23. The number of musicians in the band is 2 × 23 = 46. The number of students in the choir is 12 + 17 = 29. There are 23 + 46 + 29 = 98 musicians in total.
The answer: 98
Reverse engineering the question: There are 11 males & 12 females in the orchestra and twice that number in the band. There are 12 males & 17 females in the choir. If each musician only participates in one group, how many musicians total are there in the orchestra, the band, and the choir?

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.
The answer: 30
Reverse engineering the question:
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?