Question

Time taken by A to complete a work is 7 days
more than the time taken by B to complete the
same work. Working together they can complete
the work in 12 days. In what time can A alone
complete the work?

Answer in detail plzz
​

Answer 1

Answer:

28 days

Step-by-step explanation:

let B take x days to complete the work

A takes x+7 days to complete the work

they together take 12 days

in 1 day B works 1/x

and A works 1/(x+7)

1/x+1/(x+7)=1/12

2x+7/x^2+7x=1/12

24x+84=x^2+7x

x^2-17x-84=0

x^2-21x+4x-84=0

x(x-21)+4(x-21)=0

(x-21)(x+4)=0

x=21

A takes x+7 days=28 days