A rectangular sheet of paper is of length 1.2 m and width 21 cm. Find the ratio of width of the paper to its length.

Given,
Width of rectangular sheet = 21 cm
Length of rectangular sheet = 1.2 m
= 1.2$\times$ 100 cm = 120 cm [$\because$ 1 m = 100 cm ]
(0.5 mark)

Ratio of width to length = $\frac{21cm}{120cm}$
(0.5 mark)

$=\frac{7}{40}=7:40$ [on dividing numerator and denominator by 3]
(1 mark)

Hence, the ratio of width of the paper to its length is 7 : 40.