smc

Converting the word problem in to an equation, we take x as the initial amount, we get $$x(1+\frac{p}{100})(1-\frac{p}{100})=1$$ Using, $(a+b)(a-b)=a^2-b^2$. We now simplify it to, $$x(1-\frac{p^2}{10000})=1$$ Simplifying to, $$x(\frac{10000-p^2}{10000})=1$$ Dividing both sides by $\frac{10000-p^2}{10000}$, we get the value of x. $\boxed{\frac{10000}{10000-p^2}}$