② the associative law of addition A+(B+C) = (A+B)+C;

(3) There is a number 0, so that 0+a = a+0 = a;

Multiplication: commutative law a*b = b*a

The law of association a*(b+c)=a*b +a*c

Distribution rate a*b+a*c= a*(b+c)

Subtraction: a-b-c=a-(b+c)

Division: a÷b÷c=a÷(b×c)