1)найди значение выражения 3/7*(1/3+4/9) 2) сделай деянья а)4/15 / 2/5 б)5/6

1)  3/7 * (1/3 + 4/9) = 3/7 * (3/9 + 4/9) = 3/7 * 7/9 = 3/9 = 1/3;

2)

а) 4/15/2/5 = 4/15 : 2/5 = 4/15 * 5/2 = 2/3;

б) 5/6/30  = 5/6 : 30 = 5/6 * 1/30 = 1/6 * 1/6 = 1/36;

в) 20/ 2/1/2 = 20/5/2 = 20 * 2/5 = 4 * 2 = 8; 

г) 2 1/4 / 3  = 9/4/3 = 9/4 * 1/3 = 3/4 = 0,75;

д) 15 / 12 = 15 : 12 = 1,25;

3)

4/5 - 1/4 / 5/6 = 4/5 - 1/4 * 6/5 = 4/5 - 6/20 = 0,8 - 0,3 = 0,5.