A picture is painted on a cardboard 8 cm long and 5 cm wide such that there is a margin of 1.5 cm along each of its sides. Find the total area of the margin.
Length (l) of cardboard = 8 cm
Breadth (b) of cardboard = 5 cm
Area of cardboard including margin = l × b = 8 × 5 = 40 cm2
From the figure, it can be observed that the new length and breadth of the cardboard, when margin is not included, are 5 cm and 2 cm respectively.
Area of the cardboard not including the margin = 5 × 2 = 10 cm2
Area of the margin = Area of cardboard including the margin − Area of cardboard not
including the margin
= 40 − 10 = 30 cm2