This question was reported to be attempted by majority of the candidates and they performed well in it.  However, in part (a), it was also reported that a good number of the candidates could not manipulate the negative powers involved.  Some candidates wrote 2-1 as 2 – 1 and this affected their final answer.
Candidates were expected to subtract  from 1 to have 1 -    =  =
Thereafter, they would find -½ =  ½ = .  The fraction has to be inverted because of the negative power.  This fact eluded some candidates.
6- ½ = 6 = 8.  Similarly, 2-1 = 1 = .  Therefore, 6- ½  x 2-1 = 8 x ½  =  = 4.

In part (b), candidates were able to show that if  is the exterior angle, then the interior angle = 108 + .  Now, interior angle + exterior angle = 180o i.e.  + 108 +  = 180o.  Solving this equation gave  = 36.  The number of sides was obtained by dividing 360o by the value of the exterior angle which gave  = 10 sides.