Q.3 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 = 8 cm, breadth = 5 cm

Area of the cardboard = l × b
\( = 8 cm × 5 cm = 40 cm^2\)

Width of the margin = 1.5 cm

Length of the inner cardboard= 8 cm – 1.5 × 2 cm

= 8 cm – 3 cm = 5 cm

Breadth of the inner cardboard= 5 cm – 1.5 × 2 cm

= 5 cm – 3 cm = 2 cm

Area of the inner rectangle = l × b

= 5 cm × 2 cm = 10 \(cm^2 \)

Area of the margin\(= 40 cm^2 – 10 cm^2 = 30 cm^2 \)
Hence, the required area = 30\( cm^2\)