11/14 - 7/10 - 21/100 - 13/14 =
= (11/14 - 13/14) - (7/10 + 21/100) =
= (11-13) / 14 - (7/10 * 10/10 +21/100) =
= (-2) /14 - (70/100 + 21/100) =
= -1/7 - 91/100 =
= -1/7 *100/100 - 91/100 *7/7 =
= -100/700 - 637/700 =
= (-100-637) /700 =
= -737 / 700 = -1,05