Question 34721
Let a = number of bricks per hour laid by the apprentice.
So, 2a is the number of bricks laid by the experienced bicklayer.


Working together for 6 hours, they lay (2a+a) bricks in an hour, so after 6 hours... 6(2a+a) --> 6(3a) --> 18a.


Then the apprentice is left to finish the work, taking 10 hours --> 10a bricks in total.


So, the job laid 18a + 10a bricks --> 28a.


Now, the question says how many hours would it take the experienced bricklayer to lay this many bricks?


well, his rate is 2a and the number of hours is the unknown...call it x --> 2ax. And this has to equal the total from the first way: 28a. So,


2ax = 28a
2x = 28
x = 14


jon.