Two questions are very similar, why one of them is "and", one of them is "if....then"?

Step 7 of 8 There is a student in this class who has been in every room of at least one building on the campus If P(:,y) isz has been in y", Q(x,2) isx has been in z", the domain is x are the students in this class and y are the buildings in the campus and z are the rooms. Thus, the required expression is3ayvz(P(z.y)->0(x.2)). Comment Step 8 of 8 Every student in this class has been in at-least one room of at least one room of every building on the campus. If P(z,y) is z has been in y", Q(x,z) is x has been in z", the domain is x are the students in this class and y are the buildings in the campus and z are the rooms. Thus, the required expression is VxVy3x(P(z,y)^Q(x,z)) Thus the required result is found