The area of a rectangular piece of cardboard is 36 sq cm and its length is 9cm. What is the width of the cardboard?

Dear student,
Area of a rectangular piece of cardboard = 36 cm²
Length of the cardboard = 9 cm
Then, ----------
Area = Length × Width
=> 36 = 9 × Width
=> Width = 36/9
=> Width = 4 cm

Regards.