18 5/12-7/12∙119/21-17/72∙2/3

18 5/12 -7/12 *119/21 -17/72 *2/3= 14 103/108решим по действиям:1)7/12 * 119/21=(7*119)/(12*21)=119/36=3 11/36;2)17/72 * 2/3=(17*2)/(72*3)=17/108;3)18 5/12 - 3 11/36= 18 5*3/12*3 - 3 11/36=18 15/36 - 3 11/36=15 4/36=15 1/9;4)15 1/9 - 17/108= 15 1*12/9*12 - 17/108= 15 12/108 - 17/108= 14 120/108 - 17/108= 14 103/108Ответ: 14 103/108.