Divide the sum of and by their differ-renice.

By what number should be divided to get ?

Divide the sum of and by the product of and

Fill in the blanks:

(i) (ii)

(iii) (iv)

(i) Are rational numbers always closed under division?

(ii) Are rational numbers always commutative under division?

(iii) Are rational numbers always associative under division?

(iv) Can we divide 1 by 0?