Ratio analysis

Dear Sir,

For questions that require ratio analysis such as calculating the gross profit margin, shall we show the workings/calculations or formulas?

If there are a few years of financial data in the question, can the comparison only done for the final year with first year?

Some textbooks mention its pointless to show the calculations as it was a waste of time but some did say it was recommended to show the workings for all form of questions that require calculations as it is believe that examiner will award marks for these workings.

Please kindly advise. Thanks in advance