If the compound interest on a certain sum of money for 2 years at 5%…

Formula used-

Amount = P$(1 \;+\; \frac{R}{100})^t$

Compound Interest = Amount - Principal

Here, Compound interest = Rs 328 , R = 5%, t = 2 years 

328 =  P$(1 \;+\; \frac{5}{100})^2$ - P

⇒ 328 = P[$(\frac{21}{20})^2 - 1$]

⇒ 328 = P[$\frac{441}{400}$ - 1]

⇒ 328 = P[$\frac{41}{400}$]

⇒     P    = $\frac{328 \times 400}{41}$  

⇒     P    = 3200

Thus, Sum borrowed is Rs 3200