5 bricklayers can lay a total of 50 bricks in 30 minutes.How many bricklayers will be required to lay a total of 60 bricks in 20 minutes?

9

You can calculate the hourly rate of each bricklayer like this: 5 bricklayers laying 50 bricks in 30 minutes means 1 bricklayer will lay 10 bricks in 30 minutes. So 1 bricklayer will lay 20 bricks in 60 minutes (1 hour) Now we can see that to lay 60 bricks in 20 minutes we need a rate of bricklaying of 180 bricks per hour. (because 20 x 3 = 60 minutes so 60 x 3 = 180 bricks in 60 minutes) So the number of bricklayers to lay at this pace is 180 bricks in an hour divided by the rate of one bricklayer (20 bricks per hour) So this is 180 / 20 which is 9. So the answer is 9 bricklayers.