Data Sufficiency

I spent too much time to solve questions of this type (see attached). I normally plug-in different values to solve these type of questions: Inequalitis asking if p is greather than q , etc.
I believe I should have bough MGMT Inequalitties book. However, now it's too late as I have my exam in 3 days.

So, how do we go about solving these type of questions?
Are there any good tips or tricks out there?

Thanks
M

Here it goes

a) p-q>n means, p>q+n ( since q is positive, p has to be greater than n)
But we dont know anything about q yet

b) Q>P - Nothing about N hence insufficient.

From A and B

p>(q+n) so p>n, now, if from B) Q>P

then Q>N

so P and Q are both greater than N

Thanks.

But what are the "standard" steps to solve these kind of or more difficult DS inequality problems?

M