It takes Avery 3 hours to build a brick wall while Tom can do it in 2.5 hours. If the two start working together and after an hour Avery leaves, how much time will it take Tom to complete the wall on his own?	Select the correct option.
A) 25 minutes.	B) 30 minutes.	C) 40 minutes.	D) 55 minutes	E) 1 hour and 20 minutes
Avery's efficiency is 100/3 = 33%   tom's = 100/2.5= 
<gadget id="calculator">100/2.5</gadget>
<output>40</output>
40%   they worked together for 1 hour and finished 73% of the job   remaining= 27 %   tom will complete 40% in 60 minutes , 20% in 30 minutes and ,   7% in   60*7/40= 
<gadget id="calculator">  60*7/40</gadget>
<output>21/2 = around 10.5</output>
10.5 minutes   time taken by tom to finish the remaining on his own= 30+10.5= 
<gadget id="calculator">30+10.5</gadget>
<output>40.5</output>
40.5 minutes (adjusting for the 0.333) ~ 40 minutes   ANSWER:40 minutes.
<result>C</result>
It takes Avery 3 hours to build a brick wall while Tom can do it in 2.5 hours. If the two start working together and after an hour Avery leaves, how much time will it take Tom to complete the wall on his own?