How do you find the answer y and what is the answer?

Here, You need to understand "The Linear Pair" equation, it tells, one straight line gives 180 degrees of angle (number of different angle doesn't matter)

Now, by applying this, we can get all the angles of that Pentagon:
180 - 60 = 120
180 - 70 = 110 
180 - 65 = 115
180 - 40 = 140
180 - y = 180 - y

Now, Sum of all the angles would be 540,
120 + 110 + 115 + 140 + 180 - y = 540
665 - y = 540
y = 665 - 540
y = 125

In short, Your Final Answer would be 125

Hope this helps!