It takes 10 minutes to dry the coat of a short - haired dog and twice as long for a full haired dog so they take 10 * 2 = 20 minutes to dry. He had 6 short hair dogs and they took 10 minutes to dry each so they took 6 * 10 = 60 minutes to dry. He had 9 full haired dogs that took 20 minutes to dry each so they took 9 * 20 = 180 minutes to dry. Together is takes him 60 + 180 = 240 minutes to dry all of the dogs. 60 minutes are in 1 hour and he spends 240 minutes on the dogs so he worked for 240 / 60 = 4 hours drying the dogs.
The answer: 4
Reverse engineering the question: It takes a dog groomer 10 minutes to dry a short-haired dog like a beagle. It takes him twice as long to dry a full-haired, fluffy dog like a german shepherd. One morning, he has 6 short-haired dogs to dry and 9 full-haired dogs to dry. How many hours does it take him to dry all of the dogs?

The parking lot is 400 * 500 = 200,000. There are 200,000 * .8 = 160,000 square feet of parking space. That means he can park 16,0000 / 10 = 16000 cars.
The answer: 16000
Reverse engineering the question: James paves a new parking lot. It is 400 feet by 500 feet. Only 80% of that is useable for parking. It takes 10 square feet to park a car. How many cars can be parked?

If the first car was made 10 years earlier than the second car, then the manufacture date for the second car is 1970 + 10 = 1980. The third car was manufactured 20 years after the second car was made, which is 1980 + 20 = 2000.
The answer: 2000
Reverse engineering the question: Three old cars displayed in an auction event have different manufacture dates. The first car, made in 1970, was made 10 years earlier than the second car. The third car was manufactured 20 years later after the second car was manufactured. Calculate the year that the third car was made.

If Yola currently weighs 220 pounds, then Wanda, who weighs 30 pounds more than Yola, weighs 220 + 30 = 250 pounds. Wanda also weighs 80 pounds more than Yola did 2 years ago, meaning Yola weighed 250 - 80 = 170 pounds 2 years ago.
The answer: 170
Reverse engineering the question:
Wanda weighs 30 pounds more than Yola currently. Wanda also weighs 80 pounds more than Yola did 2 years ago. How much did Yola weigh 2 years ago if she currently weighs 220 pounds?