P works twice as fast as Q. If Q alone can complete a work in 12 days, P and Q can finish the work in________days

A. 1
B. 2
C. 3
D. 4
Work done by Q in 1 day = 1/12
Work done by P in 1 day = 2 × (1/12) = 1/6
Work done by P and Q in 1 day = 1/12 + 1/6 = ¼
=> P and Q can finish the work in 4 days