Can you show us the experimental value?
So basically, the accepted value would be under the Specific heat capacity of metal (e.g. 0.90, 0.35, 0.44, 0.12).
Your experimental value would be the specific heat capacity that you got from the lab.
You would first substract the experimental value from the accepted value

and then you would divide the result by the experimental value

and then, you would multiply the result of that by a hundred to get your percentage

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The image shown is an example.
0.90 is our accepted value.
0.88 is our experimental value.
The overall percentage error I got is %2.27