Question

Можно с обеснениями плииззз

Answer 1

а) 3/14 + 5/21
14 = 7 * 2; 21 = 7 * 3;
3/14 * 3, 5/21 * 2 = 9/42 + 10/42 = 19/42.
б) 7/8 - 0,4
0,4 = 4/10
8 = 2 * 4, 10 = 2 * 5;
7/8 * 5 - 4/10 * 4 = 35/40 + 16/40 = 51/40 = 1 11/40.
в) 2/3 - (4/7 - 1/6)
2/3 * 7 * 6 - (4/7 * 3 * 6 - 1/6 * 3 * 7) = 84/126 - (72/126 - 21/126) = - 33/126 = - 11/42.