Выполните действия: 5/6*9/15-5/12*4/15; 7/18*9/14+1/3*6/7; 9/20*2/3+5/14*7/25 ; 3 3/4*2/5-3 6/25*5/27; 1 17/28*14/9+14/25*5/7

Выполним действия:

1. 5/6 * 9/15 - 5/12 * 4/15 = (5 * 3 * 3)/(2 * 3 * 3 * 5) - (5 * 4)/(3 * 4 * 3 * 5) = 1/2 - 1/(3 * 3) = 1/2 - 1/9 = 9/18 - 2/18 = 7/18.

2. 7/18 * 9/14 + 1/3 * 6/7 = (7 * 9)/(9 * 2 * 2 * 7) + (1 * 3 * 2)/(3 * 7) = 1/(2 * 2) + (1 * 2)/7 = 1/4 + 2/7 = 7/28 + 8/28 = 15/28.

3. 9/20 * 2/3 + 5/14 * 7/25 = (3 * 3 * 2)/(2 * 10 * 3) + (5 * 7)/(2 * 7 * 5 * 5) = 3/10 + 1/(2 * 5) = 3/10 + 1/10 = 4/10 = 2/5;

4. 3 3/4 * 2/5 - 3 6/25 * 5/27 = 15/4 * 2/5 - 81/25 * 5/27 = (5 * 3 * 2)/(2 * 2 * 5) - (27 * 3 * 5)/(5 * 5 * 27) = 3/2 - 3/5 = 15/10 - 6/10 = 9/10.

5. 1 17/28 * 14/9 + 14/25 * 5/7 = 45/28 * 14/9 + (2 * 7 * 5)/(5 * 5 * 7) = (9 * 5 * 14)/(2 * 14 * 9) + 2/5 = 5/2 + 2/5 = 25/10 + 4/10 = 29/10 = 2 9/10.