**Hint:**
Basically, you want $$P(1+\frac{R}{100})(1-\frac{R_1}{100})= P$$ $$\implies 1-\frac{1}{(1+\frac{R}{100})} = \frac{R_1}{100}$$ $$\implies R_1 = \, ?$$
where $R_1$ is the required rate of reduction.
**Hint:**
Basically, you want $$P(1+\frac{R}{100})(1-\frac{R_1}{100})= P$$ $$\implies 1-\frac{1}{(1+\frac{R}{100})} = \frac{R_1}{100}$$ $$\implies R_1 = \, ?$$
where $R_1$ is the required rate of reduction.