so assuming that 25 cm is the area or 25 square cm then each cake (assuming it's a square) is 5cm by 5cm
so we find the total area of the baking tray and divide by 25
area=legnth times width
area=700 times 500
area=350,000
divide by 25
350,000/25=70,000/5=14,000
14,000 cakes will bet on the baking sheet