Вычислите устно: а)1/4-3/4= 3/8-5/8= 4/9-7/9 б)1/6-1= 5/7-1= 11/15-2= в)0-2/9= 0-(-5/6)= 0-(-1,5)=

а) 1/4 - 3/4 =(1 - 3)/4 = -2/4 = -1/4;

3/8 - 5/8 = (3 - 5)/8 = -2/8 = -1/4;

4/9 - 7/9 = (4 - 7)/9 = -3/9 = -1/3;

б) 1/6 - 1 = 1/6 - 6/6 = (1 - 6)/6 = -5/6;

5/7 - 1 = 5/7 - 7/7 = (5 - 7)/7 = -2/7;

11/15 - 2 = 11/15 - 30/15 = (11 - 30)/15 = -19/15;

в) 0 - 2/9 = -2/9;

0 - (-5/6) = 5/6;

0 - (-1,5) = 1,5.