A is 2 times as fast as B. A alone can do the work in 20 days. If A and B work on alternative days, beginning with A, in how many days will the work be completed?	Select:
A) 23 B) 22 C) 21 D) 24 E) 26
A can finish 1 work in 20 days   B can finish 1/2 work in 20 days - since A is 2 faster than B   This means   B can finish 1 work in 20*2= 
<gadget id="calculator">20*2</gadget>
<output>40</output>
40 days   Now using the awesome GMAT formula when two machines work together they can finish the job in= AB/ (A+B) = 20*40/(20+40) = 13 days   Since they alternate on days, it will take them double this time so total time = 13 * 2= 
<gadget id="calculator">13 * 2</gadget>
<output>26</output>
26 days   So answer is 26
<result>E</result>
A is 2 times as fast as B. A alone can do the work in 20 days. If A and B work on alternative days, beginning with A, in how many days will the work be completed?