A can build up a wall in 8 days while B can break it in 3 days. A has worked for 4 days and then B joined to work with A for another 2 days only. In how many days will A alone build up the remaining part of wall?
Choose the correct answer:
A) 13 1⁄3 days
B) 7 1⁄3 days
C) 6 1⁄3 days
D) 7 days
E) None of these
A’s one day’s work = 1⁄8th work.   B’s one day’s work = 1⁄3rd work.   ∴ A’s 4 day’s work = 4 × 1⁄8 = 1⁄2nd work   ∴ In next two days, total wall = 1⁄2 + 2(1⁄8) - 2(1⁄3) = 1⁄12th wall   Remaining wall = 1 - 1⁄12 = 11⁄12th   Now, 1⁄8th wall is built up by A in one day.   ∴ 11⁄12th wall is built up by A in 8 × 11⁄12 = 71⁄3 days.   Answer 7 1⁄3 days
<result>B</result>
A can build up a wall in 8 days while B can break it in 3 days. A has worked for 4 days and then B joined to work with A for another 2 days only. In how many days will A alone build up the remaining part of wall?