The price of a chocolate is increased by x% and then reduced by x%. The new price is 96.76% of the original price. Then x is:

The value of $x$ is 18. The two price multipliers give $(1+x/100)(1-x/100)=1-(x/100)^2=0.9676$, so $(x/100)^2=0.0324$ and $x/100=0.18$ for the stated increase. The value 36 adds the two 18% rates instead of reporting the single rate.