Can you solve the blue line puzzle? There are two walls-one is 5 units tall, and the other is 3 units tall. There are two ladders, and the ladders connect the top of each wall to the bottom of the other. At what height do the ladders intersect? This problem can also be applied to the time it takes people to work together versus alone. For example, if you take 8 hours to do a job, and another person takes 3 hours to do the same job, you can use similar math as the ladder problem to find out how much time it will take to complete the job together.