Given: A alone can complete a work = 10 days
A and B together complete the work in 6 days
Formula: Total work = Efficiency × Time
Calculation: Let total work be 30 (LCM of 10 and 6)
Efficiency of A = 3 units/day
Efficiency of (A + B) = 5 units/day
Efficiency of B = 5 – 3 = 2 units/day
Time taken by B to complete the work, x = 30/2 = 15 days
Alternate Solution We know, Efficiency ∝ 1/Time
According to question,
+= ⇒
=− ⇒
= ⇒
== ⇒
x=15