A project has 75 activities but we have only a partial information as shown below: activity =F, duration =55 days, IP= not given activity =K, duration =49 days, IP= not given activity =P, duration =38 days, IP= not given activity =C, duration =30 days, P= not given activity =A, duration =40 days, IP=F,K activity =L, duration =18 days ,IP=K,P activity =Q, duration =33 days, IP=P, activity =B, duration =28 days, IP=P,C If ES(F)=80,ES(K)=76,ES(P)=63 and ES(C)=73, find the value of EF(L)