A picture is painted on a piece of cardboard 8 cm long and 5 cm wide, with a 1.5 cm margin on all sides. What is the total area of the margin?

Given,

When the margin is included:

The length of the cardboard = 8 cm

The breadth of the cardboard = 5 cm

The area of the cardboard = length × breadth

                                      = 8 × 5 = 40 cm²

When the margin is not included:

The new length of the cardboard = 8 - 1.5 -1.5 = 5 cm.

The new breadth of the cardboard = 5 - 1.5 - 1.5 = 2 cm.

The new area of the cardboard = 5 × 2 = 10 cm²

Then, the area of the margin = Area of the cardboard when the margin is included – Area of the cardboard when the margin is not included.

= 40 – 10

= 30 cm²

Therefore, the total area of the margin is 30 cm².