A and B can do a piece of work in x days. If B increases its efficiency by 20% the work can be completed in 2 days less. if A alone can do a work in 30 days den B can complete the whole work in?????? solution plz

Ans. 20 days. Sol : One day's work done by A & B individually be Y% n Z%. so total work done will (Y+Z) %.. now (Y+Z)% *X = 100%. now now (Y+Z) increases y 20% so X must decrease y 16.66% or y 1/6, (s the work done is constant) which is given that its 2 days less ... so 1/6*X = 2 => X = 12 days. now, A's daily contribution = 3.33%. so B's must be 5% bcoz as perl question , (5+3.33)*12 = 100. Hence, B alone can finish the work in 20 days!!