First aligning both the numbers according to Place Value table,
For doing subtraction,
One's digit of subtrahend must be subtracted from one's digit of minuend, ten's digit of subtrahend must be subtracted from ten's digit of minuend and so on ...
So, first subtracting the digits at Ones place,
$6 - 3 = 3
Now subtracting the digits at Tens place, we get
2−3, which is not possible
We will borrow 1 hundreds from 3 hundreads. 1 hundreds = 10 tens.
So, digit at Tens place will become (10+2)−3=12−3=9