Question 140766
First, the area of 1 square tile is 25cmx25cm=625sq cm.
Since you need 240 tiles to cover the whole rectangular floor, you'll have the area covered likewise. So, total 240 tiles times each area of 625sq.cm per tile = 150,000sq cm. = 15 sq.meter (take note 1 sq meter= 10,000 sq cm). 

Therefore, to get the width we'll go to the Area(A) of rectangle=(Length)(Width)
15 sq m.= (5m)(W)
W= 3 meters. 
Thank you,
Jojo