Reasoning and answer: Mike is using 40 blocks / 2 = 20 blocks of type B. He uses in total 40 blocks + 20 blocks = 60 blocks of type A and B. So he is going to use 150 blocks - 60 blocks = 90 blocks of other types.
The answer: 90
What was the question?
Question: Mike is building a bridge out of LEGO blocks. To be successful he needs at least 40 bricks of type A, and half that many of type B. In total, he needs to use 150 bricks. How many bricks of other types than mentioned is he going to use?


Calculus: 4 years. Algebra: 4(2) = 8 years. Statistics: 8(5) = 40 years. Total number of years taught: 4 + 8 + 40 = 52 years.
The answer: 52
Reverse engineering the question: Devin teaches one math course per year. He taught Calculus for 4 years, Algebra for twice as many years, and Statistics for 5 times as long as he taught Algebra. How many years has Devin taught?


Reasoning and answer: Maria has 8 + 10 = 18 black pens. Maria has 8 + 7 = 15 blue pens. Maria has 8 + 18 + 15 = 41 pens in total.
The answer: 41
What was the question?
Question: There are 8 red pens in Maria's desk drawer. There are 10 more black pens than red pens. There are also 7 more blue pens than red pens. How many pens are there in all?


Grace can read 200 / 20 = 10 pages in 1 hour. So she can finish a 250 - page book in 250 / 10 = 25 hours.
The answer: 25
Reverse engineering the question: Grace can read a 200-page book in 20 hours. How long would it take her to finish reading a 250-page book at this constant rate?


Reasoning and answer: Since the father dug a hole with a rate of 4 feet per hour, if the father took 400 hours digging the hole, he dug a hole 4 * 400 = 1600 feet deep. Twice the depth of the hole that Michael's father dug is 2 * 1600 = 3200 feet. Michael wants to dig a hole 400 feet less than twice the depth of the hole that his father dug, meaning he wants to dig a hole 3200 - 400 = 2800 feet deep. To dig a hole that is 400 feet less than twice as deep as his father's hole working at a rate of 4 feet per hour, Michael will have to work for 2800 / 4 = 700 hours.
The answer: 700
What was the question?
Question: Michael wants to dig a hole 400 feet less deep than twice the depth of the hole that his father dug. The father dug a hole at a rate of 4 feet per hour. If the father took 400 hours to dig his hole, how many hours will it take for Michael to dig a hole that is 400 feet less than twice as deep as his father's hole working at the same rate?


Reasoning and answer: He can jump 3 * 60 = 180 times per minute. So he can jump 180 * 60 = 10,800 per hour. So it would take him 54,000 / 10,800 = 5 hours.
The answer: 5
What was the question?
Question:
Mark wants to set the record for most consecutive ropes jumped. The record is 54,000. He can jump 3 times a second. How many hours would he need to jump rope?