1)14*(1/2+1/3+1/4)= 2) 1/3*6/7-1/7*3/4= 3) 1/2*2/3*3/4*5/6*23/24*24/25=

14 * ( 1/2 + 1/3 + 1/4 ) = 14 * ( 6/12 + 4/12 + 3/12 ) = 14 * 13/12 = 91/6 = 15 1/6

1/3 * 6/7 - 1/7 * 3/4 = 2/7 - 3/28 = 5/28

1/2 * 2/3 * 3/4 * 5/6 * 23/24 * 24/25 = это уже по действиям решать = 23/120
1) 1/2 * 2/3 = 1/3
2) 1/3 * 3/4 = 1/4
3) 1/4 * 5/6 = 5/24
4) 5/24 * 23/24 = 115/576
5) 115/576 * 24/25 = 23/120