Question

A can build up a structure in 8 days and b can break it is 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 the structure?

Answer 1

Solution:  

A can build up a structure of  1 day's work = 1/8

B can build up a structure of 1 day's work in breaking the building

= 1/3

Now, according to the question,

A can build up of structure of 4 day's work = 4×1/8=12

Now, A and B can build up of structure of 2 day's work

=> 2(1 / 8−1 / 3)=2×−5/24

=> −10 / 24

Total work done in 6 days

12+(−10 / 24) = 12−10 / 24

=> 11 /  12

Remaining Work =  1-11 / 12 =11 / 12

Now,

A can complete the work, so A can complete in x days.

1/8×x=11 /12

=> x=11×8 / 12

x=11×2 / 3

=7.33 days.

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@GauravSaxena01