There are 10 millimeters in a centimeter. If we convert the tray into centimeters, we get a 60 cm x 50 cm tray. I assume the cake tin in a 25 cm² tin, because it needs two dimensions. I find it best, in this scenario, to draw a picture. On a 50 cm side, you can fit two tins because 25 only goes into 50 twice. The same goes for the 60 cm side. If you draw a picture, you'll see that only four 25 cm cake tins will fit.
