Пошаговое объяснение:
1. 6 3/13*8 11/19+6 3/13*4 8/19 = 6 3/13 *(8 11/19 + 4 8/19) = 6 3/13 * 13 = 81/13 * 13 = 81
2. 3 3/7*9 5/12-3 3/7*2 11/18 = 3 3/7 * (9 5/12 - 2 11/18) = 3 3/7 *(9 15/36 - 2 22/36) = 3 3/7 * 6 29/36 = 24/7 * 245/36 = 70/3 = 23 1/3
