Вычислите: а)-7/9-(2 5/12-11/20) б)7/18*(-9/14)-15/16*3 3/8

а) -7/9 - (2 5/12 - 11/20) = -7/9 - (2 * 12 + 5)/12 + 11/20 = -7/9 - 29/12 + 11/20 = -7/9 - 5 * 29/60 + 3 * 11/60 = -7/9 - 145/60 + 33/60 = -7/9 - 112/60 = -7/9 - 28/15 = -35/45 - 84/45 = -119/45;б) 7/18 * (-9/14) - 15/16 * 3 3/8 = -(7 * 9)/(14 * 18) - 15/16 * (3 * 8 + 3)/8 = -1/4 - 15/16 * 27/8 = -1/4 - 405/128 = -32/128 - 405/128 = -437/128.