2、600×( 1- 1/ 12)=550 600-600× 1/ 12=550

3、 16×( 1- 1/4)= 12 16- 16× 1/4= 12

These topics basically regard the front as a whole 1. Compared with the previous 1, what is missing and what is more is calculated by the whole 1. Add more, and subtract less. The result is multiplied by the actual number of integer 1, and that's it.