7 1/2 *(-1/5) + (-1 2/3)*(-9/10) - 17 29/30 =
= 15/2 *(-1/5) + 5/3 * 9/10 - 17 29/30 =
= - 3/2 + 3/2 - 17 29/30 = - 17 29/30;
(-2 13/25):(-2 7/10) - 17 25/47 : (-17 25/47):(-17
25/47) - 4 3/5 =
= 63/25 * 10/27 - 47/824 - 4 3/5 =
= 126/135 - 47/824 - 621/135 =
= - 11/3 - 47/824 = - 3 2/3 - 47/824 = - 3 1789/2472