Question

Person A finish a piece of work in 15 days and B in 20days.They work together for 4 days and B goes away. In how many days A finish work<br />

Answer 1

Answer :-

A will take 8 more days to finish the work.

Solution :-

A can finish a piece of work in 15 days

So A's one day work = 1/15

B can finish a piece of work in 20 days

So B's one day work = 1/20

A and B one day work = 1/15 + 1/20

= (4 + 3)/60

= 7/60

In 4 days A and B work = 4 * 7/60

= 7/15

Remaining work after 4 days which A alone has to do = 1 - 7/15

= (15 - 7)/15

= 8/15

= 8 * 1/15 ( 8 * A's one day work)

So A will take 8 more days to finish the work.

Answer 2

$\huge{\mathfrak{</p><p><strong>Answer:</strong></p><p>}}$

$\large{\bf{A\:can\:finish\:a\: work \:in\:15\:day}}$

$\large{\bf{So,\:A\:one\:day\: work\:= \:1/15}}$

$\large{\bf{B\:can\:finish\:a\: work \:in\:20\:day}}$

$\large{\bf{So,\:B\:one\:day\: work\:= \:1/20 }}$

$\large{\bf{A\:and\:B\:one\:day\: work\:= \:1/20 + 1/15 }}$

$\large{\sf{(3 + 4)/60}}$

$\large{\sf{7/60}}$

$\large{\bf{In \:4\: days \:A\:and\:B\:work. }}$

$\large{\sf{4 × 7/60}}$

$\large{\sf{7/15}}$

$\large{\bf{Remaining \:work\:after\:4 \:days \:which \: A \:alone \: has \:to \:do. }}$

$\large{\sf{(15 - 7)/15}}$

$\large{\sf{8/15}}$

$\large{\sf{8 × 1/15}}$

$\huge{\bf{So, \:A \:will\:take\:8\:more \:days\:to \:finish\:a \:work. }}$