a) $$2,25 : 4,5 = \frac{2,25}{4,5} = \frac{225}{450} = \frac{1}{2} = 0,5$$
б) $$0,44 : 6,6 = \frac{0,44}{6,6} = \frac{44}{660} = \frac{2}{30} = \frac{1}{15}$$
в) $$3,78 : 4,2 = \frac{3,78}{4,2} = \frac{378}{420} = \frac{9}{10} = 0,9$$
г) $$0,8 : 2,8 = \frac{0,8}{2,8} = \frac{8}{28} = \frac{2}{7}$$