Answer:
Parallel flow

Step-by-step explanation:
Given that
For hot fluid
Inlet temperature=65 C
Outlet temperature=40 C
For cold fluid
Inlet temperature=15 C
Outlet temperature=30 C
Here is only temperature is given and did not provide the information about heat capacity of fluids so by only seeing temperature we can not predict the types of heat exchanger. But there is not too much difference in temperature of exits fluids so we can say that this is parallel flow heat exchanger.
Effectiveness of heat exchanger given as


