mirhaque wrote:

thanks;)

it is something killing.

a+b can do 50 pages in 6 minuets

a+b can do 80 pages in (6x80)/50 = 48/5 minuets ...................i

a can do 40 pages in (b+4) minuets

a can do 80 pages in 2(b+4) minuets

a can do 80/2(b+4) = 40/(b+4) pages in 1 minuet

b can do 40 pages in b minuets

b can do 80 pages in 2b minuets

b can do 80/2b= 40/b pages in 1 minuet

a+b can do [40/(b+4)]+[40/b] pages in 1 minuet

a+b can do 1 pages in 1/[40/(b+4)]+[40/b] minuetss

a+b can do 80 pages in {80/[40/(b+4)]+[40/b]} minuets ...............ii

the time taken by a+b in eq i must equal to the time taken by a+b in eq ii. therefore

48/5 minuets = 80/[{40/(b+4)}+(40/b)]minuets

5b^2-28b-96 = 0 ...................................iii

solving the above eq iii,

b = 8

a = b+4 = 12

a takes to complete 40 pages (b+4) = 12 minuets.

a takes to complete 80 pages 2(b+4) = 12x2=24 minuets.

its not an easy question. i did not like it. cus took too much