Thomas takes 7 days to paint a house completely whereas raj requires 9 days to paint the same house completely. how many days will take to paint the house if both them work together ?

A. 3

B. 5

C. 4

D. 8

Answer : C. 4

Explanation:

No. of days taken by Thomas = 7 days.
So work done by thomas in a day = 1/7

No. of days taken by Raj = 9 days.
Work done by other in a day = 1/9

Work done by both in a day = 1/t

1/7 + 1/9 = 1/t
16/63 = 1/t.
16t = 63.
Days required by both (t) = 63/16.

Total no. of days taken to paint the house is (approx.) = 4 days .

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