Plz solve - ratio analysis

Operating Ratio-Operating expense   x 100

                             Net sales

Operating expense-Cost of Good sold

Cost of good sold=Sales-Gross profit

                         =180000-40000

                        =120000

Net sales=180000(given)

Operating ratio=120000 x100

                      180000

                     =66.66% 

sir i too got the same answer as 66.66 but in the book the answer was given as 91.11%. I think there may be a printing mistake na...

Sorry ,my above calculation is wrong ,I didn't consider closing stock balance and  net profit.

Correct calculation is -

COGS=Opening stock +purchases +direct expenses-closing stock.

COGS =Sales-Gross profilt 

           =180000-40000

          =120000

Now .we put the value of COGS in above formula ,and will get the sum of opening stock ,purchases,and direct expense

    120000=Opening stock+Purchases+Dorect expense-56160

    Thus Sum of Opening stock,purchases ,direct exp=176160

 The difference between two sides of profilt& loss a/c will be administrative exp (operating exp)

=Sales+Closing stock-Opening stock-Purchases -Direct Exp-Gross profit

=180000+56160-176160-40000

Administrative exp=20000

Net Profit =16000(Given)

The difference between Gross profit and net profit will also assumned as operating expense as non operating exp not given in question ie (intt on deb not available ),we take as selling distribution exp 

 =Gross profit-Net profit

=40000-16000

Selling exp=24000

Hence Operating ratiois=COGS+Adm exp+Selling expx100

                                     Net sales 

                                =120000+20000+24000x100

                                          180000

                             =164000x100

                               180000

                            =91.11%