Question

How much percent above the cost price should a shopkeeper mark his goodles such that after allowing a discount of 9 percent he still gains 12 percent?

Answer 1

let the MP be x
  after allowing a discount of 9%
    0.91x
still gains 12%
1.12of CP=0.91x
⇒CP=0.8125x
so he should mark his price up by 0.1875x
% above CP=23.07%

Answer 2

Lets assume the CP as 100.
Then SP according to the given gain=  100 x CP   =  112
                                                              100+G%
We know the SP and D% now we'll find the MP=
   100      x SP    =       100    x 112  =  123.5 or     123   7     (no. is in mixed form.)
 100-D%                   100- 9                                            91
so he should mark the MP 23.5% above the CP
: )