What single rate of discount is equivalent to the series of discounts: $13\mathrm{\%},23\mathrm{\%},25\mathrm{\%}$, and $28\mathrm{\%}$ ?

Answer = $\mathrm{\%}$ (written as a percentage rounded to two decimal places)

Step 1 ：Let's start with an initial value of $100$

Step 2 ：Apply the first discount of $13\mathrm{\%}$, which gives us a new value of $100-(100\times \frac{13}{100})=87$

Step 3 ：Apply the second discount of $23\mathrm{\%}$, which gives us a new value of $87-(87\times \frac{23}{100})=66.99$

Step 4 ：Apply the third discount of $25\mathrm{\%}$, which gives us a new value of $66.99-(66.99\times \frac{25}{100})=50.2425$

Step 5 ：Apply the fourth discount of $28\mathrm{\%}$, which gives us a final value of $50.2425-(50.2425\times \frac{28}{100})=36.1746$

Step 6 ：The equivalent single rate of discount is the percentage decrease from the original value to the final value, which is $(100-36.1746)=63.8254\mathrm{\%}$

Step 7 ：Rounded to two decimal places, the equivalent single rate of discount is $\boxed{{\displaystyle 63.83\mathrm{\%}}}$