A and B can together finish a work in 40days. They worked together for 10days and then B left. After another 21 days, A finished the remaining work. In how many days A alone can finish the job?
Pick
A) 10  B) 25  C) 60  D) 30  E) 28
A+B 10days work = 10*1/40 +  10= 
<gadget id="calculator">+  10</gadget>
<output>10</output>
10*1/40= 1/4   Remaining work = 1-1/4 = 3/4   3/4 work is done by A in 21 days   whole work will be done by A in  21*4/3= 
<gadget id="calculator"> 21*4/3</gadget>
<output>28</output>
28 days   Answer is 28
<result>E</result>
A and B can together finish a work in 40days. They worked together for 10days and then B left. After another 21 days, A finished the remaining work. In how many days A alone can finish the job?