<span>Difference of squares method is a method that is used to evaluate the difference between two perfect squares.
For example, given an algebraic expression in the form:
can be factored as follows:

From the given expressions, the only expression containing two perfect squares with the minus sign in the middle is the expression in option A.
i.e.

which can be factored as follows:

.</span>
You first convert everything to minutes
3hrs= 60x3=180mins
1hr= 60x1=60mins
then you add 20 to 180
200
and you also add 48 to 60
104
200-104=
96
Then you convert to hrs and mins
96-60=36
1hr 36mins