16. Oblicz: 1 3/4 * 1 1/7 - 3 / (4 1/2) =; 1 5/7 * (2 3/4 - 1 2/3 / 4) =; 3 1/3 * (2 1/4 - 1 1/2 / 5) =; (3 1/4 + 1/2)/(3 1/3 * (1 5/6 - 1 1/12)) =.