Given: f(x)=∣2x2+5∣x∣−3∣
Now, let y=∣2x2+5x−3∣
⇒y=∣2x2+6x−x−3∣
⇒y=∣2x(x+3)−(x+3)∣
⇒y=∣(2x−1)(x+3)∣
Graph of ⇒y=∣(2x−1)(x+3)∣ is given below:

Graph of f(x)=∣2x2+5∣x∣−3∣ is given below:

So, f(x) is continuous for x∈R and non-differentiable at x=±21,0
So, number of points of discontinuity=0=m
Also, number of points of non-discontinuity=3=n
⇒m+n=3