Given,
C.I that Kamla receive = Rs.210
S.I that Kamla paid = Rs.200
Time = 2 years
So,
S.I \(=\frac{P \times R \times T}{100}\) \(=\frac{(P \times R \times 2)}{100}\) = 200
\({P}\times{R}\) = 10000 ................(i)Also,
C.I. = Total amount - Principal amount
C.I \(={P}({1}+\frac{R}{10})^T-{P}\)
\({210}={P}({1}+\frac{R}{100})^2-{P}\)
we know, (a + b)2 = a2 + b2 + 2ab
\({210}={P}({1^2}+\frac{R^2}{100^2}+{2}({1})(\frac{R}{100})-{P}\)
\(210= p({1}+\frac{R^2}{10000}+\frac{R}{50}-p\)
\(210=p({1}+\frac{R}{10000}+\frac{R}{50})-1\)
\(210= p(\frac{R^2}{10000}+\frac{R}{50})\)
\(210 =\frac{PR^2}{10000}+\frac{PR}{50}\)
from {i}, we have PR = 10000
∴ 210 \(=\frac{10000R}{10000}+\frac{10000}{50}\)
210 = R+ 200
R = 10%
From equation (i)
\({P\times R}\) = 10000
\({P\times R}\) = 10000P \(=\frac{10000}{10}\) = Rs. 1000