пример 4 5/14+(5 1/12-3 4/12)= решить уравнение 8 9/26-z=5 7/39

а) 4 5/14 + (5 1/12 - 3 4/12) = 6 3/28.
    4 5/14 = (4 * 14 + 5)/14 = 61/14.
    5 1/12 = (5 * 12 + 1)/12 = 61/12.
    3 4/12 = (3 * 12 + 4)/12 = 40/12.
 1. 61/12 - 40/12 = (61 - 40)/12 = 21/12 сократим на 3 = 7/4.
 2. 61/14 + 7/4 = (122 + 49)/28 = 171/28 = 6 3/28.
б) 8 9/26 - z = 5 7/39.
    8 9/26 = (8 * 26 + 9)/26 = 217/26.
    5 7/39 = (5 * 39 + 7)/39 = 202/39.
    217/26 - z = 202/39.
    z = 217/26 - 202/39.
    z = (651 - 404)/78.
    z = 247/78 сократим на 13 = 19/6.
    z = 3 1/6.
Проверка:
217/26 - 19/6 = (651 - 247)/78 = 404/78 на 2 = 202/39.