Number of tins =20 Weight of tins = Weight of each tin× No. of tins Weight of tins =170g×20=3400g Weight of carton =500g Total weight after packing tins = Weight of carton + Weight of tins Total weight =3400g+500g=3900g There was no option of gram ( g ) so convert the grams to kilogram by dividing the gram by 1000 3900g=3900∕1000kg=3.9kg Weight of carton when packed = 3.9 Note: Kilo means 1000