Three marchines P,Q can do a piedce of work in 7,9 and 10 days, respectively. Deu to problem in P and Q, they are working only ay 70% and 90% of their effiency, resepectively. In how many days can P,Q and R together do the work ?

Options

A. `1(2)/(3)` days
B. `2(1)/(3)` days
C. `2(3)/(2)` days
D. `3(1)/(3)` days

Answer

D