If 50 apprentices can finish a job in 4 hours, and 30 journeymen can finish the same job in 6 hours, how much of the job should be completed by 10 apprentices and 15 journeymen in one hour?  Choose the correct option
A) 1/9	B) 29/180	C) 26/143	D) 2/15	E) 39/121
50 apprentices can finish the job in 4 hours,thus:   10 apprentices can finish the job in   4*5= 
<gadget id="calculator">  4*5</gadget>
<output>20</output>
20 hours;   In 1 hour 10 apprentices can finish 1/20 of the job.   30 journeymen can finish the same job in 4,5 hours,thus:   15 journeymen can finish the job in  6*2= 
<gadget id="calculator"> 6*2</gadget>
<output>12</output>
12 hours;   In 1 hour 15 journeymen can finish 1/12 of the job.   Therefore, in 1 hour 10 apprentices and 15 journeymen can finish 1/20+1/12=2/15 of the job.   Answer: 2/15.
<result>D</result>
If 50 apprentices can finish a job in 4 hours, and 30 journeymen can finish the same job in 6 hours, how much of the job should be completed by 10 apprentices and 15 journeymen in one hour?