Question

A can do a work in 25 days which B can do in 20 days both work together for 10 days then A leave. what fraction of work B has to complete.​

Answer 1

Step-by-step explanation:

Assuming that B alone takes x days to finish the work. Then A alone can finish it in (x−6) days Now A’s one day’s work + B’s one day’s work =1/x + 1/x−6 and (A+B)’s one day’s work =1/4 1/x + 1/x−6 = 1/4 x-6+x/x(x-6) = 1/4 = 2x-6/x 2 -6x = 1/4 =8x−24=x2−6x ⇒x2−14x+24=0 ⇒x2−12x−2x+24 = 0 ⇒(x−12) (x−2) = 0 ⇒x=12 or x = 2 x cannot be less than 6. So x=12 Therefore, B also can finish the work in 12 days.