Question

do no. 4ii, 5ii, 7 iv,vi

Answer 1

4(ii). 3/10, -11/15, -10/9
Associative law:
[(3/10)+(-11/15)]+(-10/9)=(3/10)+[(-11/15)+(-10/9)]
[(9-22)/30]-10/9=3/10+[(-33-50)/45]
-(13/30)-(10/9)=(3/10)-(83/45)
(-39-100)/90=(27-166)/90
-139/90=-139/90      
Hence, LHS=RHS.

5(ii).(4/9)+[(-5/11)+(7/3)]=[(4/9)+(-5/11)]+(7/3)
  (4/9)+[(-15+77)/33]=[(44-45)/99]+(7/3)
  (4/9)+(62/33)=-1/99+(7/3)
  (44+186)/99=(-1+231)/99
  (230/99=230/99
Hence, LHS=RHS.

7(iv).(2/5)+(8/3)+(-11/15)+(4/5)+(-2/3)
  (6+40-22+12-10)/15
  (26/15).

7(vi).(3/7)+0+(4/21)+(5/14)+(-9/7)
  (126+56+105-378)/294
  (-91/294).