I think both the events are independent events bcoz the prob she studies cs any particular day is .4 and she studies Maths any particular day is .6 .
Given that she study cs on Mon then,∣
prob(Cs on Wed) = P(Cs on Tue , Cs on Wed) +P(Maths on Tue,Cs on Wed)
=P(Cs on Tue).P(Cs on Wed)+P(Maths on Tue).P(Cs on Wed)
=.4*.4 +.6*.4 =.4
In short, prob(Cs on Wed ∣ Cs on Mon ) = prob(Cs on Wed) = .4 // Independent