(0.7-11/30)*(-1 2/7) - (0.25-11/24):2 11/12 = - 5/14
0.7-11/30 = 7/10 - 11/30 = 21/30 - 11/30 = 10/30 = 1/3
1/3*(-1 2/7) = -1/3*9/7 = -3/7
0.25-11/24 = 25/100 - 11/24 = 600/2400 - 1100/2400 = - 500/2400 = -5/24
-5/24 : 2 11/12 = - 5/24 : 35/12 = - 5/24*12/35 = - 1/14
-3/7 - (-1/14) = - 6/14 + 1/14 = -5/14