Interest $I=\frac{P\times R\times T}{100}I\; =\; \backslash frac\{P\; \backslash times\; R\; \backslash times\; T\}\{100\}$
Here, $I=5400I\; =\; 5400$, $R=12\mathrm{\%}R\; =\; 12\backslash \%$, and T=3 years.
Substitute the values:
$5400=\frac{P\times 12\times 3}{100}5400\; =\; \backslash frac\{P\; \backslash times\; 12\; \backslash times\; 3\}\{100\}$

$5400=\frac{36P}{100}5400\; =\; \backslash frac\{36P\}\{100\}$

$P=\frac{5400\times 100}{36},P\; =\; \backslash frac\{5400\; \backslash times\; 100\}\{36\}\; =\; 15,000$P=365400×100​=15,000