



 
Hi Cavell, The difference is 71,700  56,876 = 14,824. But you want the difference presented as a percentage. The difficulty is that when you say percentage you should say "percentage of what". 14,824 as a percentage of the projected cost is
14,824 as a percentage of the actual cost is
An unambiguous way to express what happened is to represent the actual cost as a percentage of the projected cost.
and say
The difference is then, 100%  79.3% = 20.7%, and the "percentage of what?" question is clearly answered by the way you have reported situation in the statement above. I hope this helps,  


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