y-interceptis As given by the question
There are given that the value of x and y.
Now,
For finding the value of the slope, choose two-point from the given table
So,
Suppose the two points are:

Now,
From the formula of slope:

Where,

Put all the above value into the given formula
So,

Hence, the value of the slope is -1.
Now,
For the equation of the line that is based on the given chart, use two supposes point and the given slope.
So,
The two poin and slope is:

Then,
From the formula of two point form;

Where,

Then,
Put all the given value into the above formula
So,

Hence, the equation of the line is:

Now,
To find the y-intercept, put x=0 and solve for x
So,
The y intercept of the given equation is:

Hence, the y-intercept is (0, 6)