If 5 students stay in a room of a youth hostel, 14 students will not have a room. If 7 students stay in a room, there will be 4 vacant rooms.

(a) How many rooms does the youth hostel have?

(b) How many students are staying at the youth hostel?

(a) 19

(b) 117

(b) 117

(a) 21

(b) 119

(b) 119

(a) 23

(b) 121

(b) 121

(a) 25

(b) 123

(b) 123

None of the above