It takes Avery 3 hours to build a brick wall while Tom can do it in 4 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? Choose the correct choice.
A) 25 minutes.  B) 55 minutes.  C) 1 hour and 41 minutes  D) 1 hour and 35 minutes  E) 1 hour and 20 minutes
Avery's efficiency is 100/3 = 33%   Tom's = 100/4= 
<gadget id="calculator">100/4</gadget>
<output>25</output>
25%   they worked together for 1 hour and finished 58% of the job   remaining=42 %   Tom will complete 25% in 60 minutes , and   17% in   60*17/25= 
<gadget id="calculator">  60*17/25</gadget>
<output>204/5 = around 40.8</output>
40.8 minutes   Time taken by Tom to finish the remaining on his own= 60+40.8= 
<gadget id="calculator">60+40.8</gadget>
<output>100.8</output>
100.8 minutes (adjusting for 0.2) ~ 101 minutes   ANSWER:1 hour and 41 minutes
<result>C</result>
It takes Avery 3 hours to build a brick wall while Tom can do it in 4 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?