9 to 12 year olds
My Mobile phone is 7cm. wide and 13 cm. long.
In the phone store, they want to promote it and they have made a similar mobile, out of cardboard. Its width is 14 cm.
I like it and I’m going to make one just as big as the one they have at the store.
The cardboard costs 3 cents per square centimeter. How many cents does the cardboard of the phone cost? (I pay exactly the piece that occupies the phone).