-9

=

-9

............ addition and subtraction = subtraction.

-9*- 10

=9* 10=90 ...

-5-[-4]=

-(5-4)=- 1 ... The subtraction of two negative numbers is equal to the subtraction of positive numbers.

-7-[-8]=

-(7-8)= 1 ... Subtracting two negative numbers equals subtracting a positive number and then taking a negative number.

-9/-3

=

9/3

=3

.................................................................................................................................................................................

The result of multiplication and division with the same sign is positive

The result of multiplication and division of different symbols is negative.

......