(2,1 * 1 1/3 - 1,4 * 1/11) / (0,7 * 1 3/11) = 3,
числитель:
1) 2,1 * 1 1/3 = 21/10 * 4/3 = 14/5 = 2 4/5 (или 2,8),
2) 1,4 * 1/11 = 14/10 * 1/11 = 14/110 = 7/55,
3) 2 4/5 - 7/55 = 14/5 - 7/55 = 154/55 - 7/55 = 147/55 = 2 37/55,
знаменатель:
4) 0,7 * 1 3/11 = 7/10 * 14/11 = 49/55,
5) 2 37/55 : 49/55 = 147/55 : 49/55 = 147/55 * 55/49 = 3