A charges rupees 800/hr and B 1400/hr for typing.B's speed is 1.75 times that of A.If each of them types 140 pages in a day,then for that day what will be the average charge per person per hour?

Assuming B types 1.75 page/hour
Then A types 1 page/hour

Number of hours to type 140 pages by B = 140/1.75 = 80 hour
Number of hours to type 140 pages by A = 140/1 = 140 hour

Average cost = ( (80*1400) + (140*800) ) / (80+140) = 2,24,000/220 = 1018.18 Ans !!

Thanks a lot sanchit!
but i have a silly doubt that,like in question it was asked cost per hour per person
so there is no need to divide 1018 by 2(here 2 is taking in consideration the two people working???)
please clarify this!!