16 целых 1/4d - 5 (5d-1.8) - (3.1-8.75d)=
16.25d-25d+9-3.1+8.75d=25d-25d+9-3.1=5.9
-5/2c-10/9+4c-1.5c+7/18=-2.5c+4c-1.5c+7/18-20/18=-13/18