Pipe &lsquoA&rsquo and pipe &lsquoB&rsquo, together can fill 20% of a tank in 8 hours while pipe

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Question

Pipe ‘A’ and pipe ‘B’,

together can fill 20% of a tank in 8 hours while pipe ‘C’ takes 50 hours to empty it. Pipe ‘A’ and pipe ‘B’ were opened together. After 25 hours, pipe ‘C’ is also opened. Find the total time taken to fill the empty tank this way.

A 30 hours

B 42 hours

C 100 hours

D 49 hours

E 35 hours