A1 Date (user entered value)
B1 =Text(A1,"ddd")
C1 Arrive Time (user entered value)
D1 Dept Time (user entered value)
E1 =If(IsBlank(C1),"",Mod(D1-C1,1)*24)
F1 Afterhours Home Work (user entered value)
G1 =E1+F1
Problem:
If 'C1' is blank, then value "" placed in E1 -- which causes...