$\"\"$

The rate of interest is $\"\"$ and time is $\"\"$ .

Formula for compound interest is $\"\"$ .

Formula for amount compounded monthly is $\"\"$ .

Substitute $\"\"$ , $\"\"$ and $\"\"$ in $\"\"$ .

$\"\"$

Therefore, the principal amount is $\"\"$ .

$\"\"$

The principal amount is $\"\"$ .