8 - 4,2 : [(2)5/14 - (1)4/21]
(2)5/14 - (1)4/21 = (2 - 1) + ( 15/42 - 8/42) = 1 + 7/42 = 1 + 1/6 = (1)1/6
4,2 : (1)1/6 = 42/10 : 7/6 = 42/10 * 6/7 = 3,6
8 - 3,6 = 4, 4
5 тонн 6 цент =5600кг
5600:40=140кг или 1 цент 40 кг
57:(х:28)=19
<span>х:28=57:19
</span><span>х:28=3
</span>х=84