Пошаговое объяснение:

№2

1) -3,15 * (-2,04) = -3. 15/100 * (-2. 4/100) = -315/100 * (-204/100) = -63/20 * (-51/25) = 3213/500 = 6. 213/500

2) -7. 5/11 * 9. 1/6 = -82/11 * 55/6 = -41/1 * 5/3 = -205/3 = -68. 1/3

3) 6. 213/500 + (-68. 1/3) = 6. 213/500 - 68. 1/3 = 6. 639/1500 - 68. 500/1500 = 6. 639/1500 - 67. 2000/1500 = -61. 1361/1500