5 2/3:1,3-1 7/12*6

5 2/3 : 1/3 - 1 7/12 * 6 = 7 1/2

5 2/3 : 1/3 - 1 7/12 * 6 = 17/3 : 1/3 - 19/12 * 6 = 17/3 * 3 - 19/12 * 6 = 17 - 19/12 * 6 = 17 - 19/2

(17 * 2 - 19 * 1) / 2 = (34 - 19) / 2 = 15/2 = 7 1/2

7 1/2 = 7.5