From the information given, the tins are circular /cylindrical because they have a diameter.
So we need to find out the base area of each tin .
Base Area = π r²
radius here will be 25/2 = 12.5
Area = 3.14 × 12.5 ×12.5
Area = 490.6cm²
For the tray the dimensions are 600mm and 500mm which seem to allude the trays are of a regular shape such as a rectangle. Let us assume it is so.
600mm = 60cm, and 500mm = 50cm
Area = L × w
Area = 50 × 60 = 3000cm²
Each tray will fit 3000 ÷ 490.6 = 6.1
6 cake tins will fit into one tray