It takes Avery 2 hours to build a brick wall while Tom can do it in 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) 1 hour and 30 minutes	E) 1 hour and 20 minutes
Avery's efficiency is 100/2= 
<gadget id="calculator">100/2</gadget>
<output>50</output>
50%   Tom's= 100/5= 
<gadget id="calculator">100/5</gadget>
<output>20</output>
20%   they worked together for 1 hour and finished 70% of the job   remaining= 30 %   Tom will complete 20% in 60 minutes , and   10% in   60*10/20= 
<gadget id="calculator">  60*10/20</gadget>
<output>30</output>
30 minutes   Time taken by Tom to finish the remaining on his own= 60+30= 
<gadget id="calculator">60+30</gadget>
<output>90</output>
90 minutes   ANSWER:1 hour and 30 minutes
<result>D</result>
It takes Avery 2 hours to build a brick wall while Tom can do it in 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?