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A can complete a work in 20 days and B in 30 days. A worked alone for 4 days and then B completed the remaining work along with C in 18 days. In how many days can C working alone complete the work ?

A) 12
B) 68
C) 72
D) 90

Correct Answer:




D) 90

Description for Correct answer:

Work done by A in 4 days = \( \Large \frac{4}{20}=\frac{1}{5} \)

Remaining work = \( \Large 1-\frac{1}{5}=\frac{4}{5} \)

Let C can working alone complete the work in x days.

According to the question,

\( \Large \frac{18}{30}+\frac{18}{x}=\frac{4}{5} \)

=> \( \Large 18(x+30)\times 5 \)=\( \Large 4\times 30x \)

=> 90x+2700=120x

=> 30x=2700

x=90 days

Part of solved Time and work questions and answers : >> Aptitude >> Time and work

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