Answer:
See below:
Step-by-step explanation:
To find the slope, we use the following formula:

For this case, we can use (6,60) as the first set of points.
We can use (4,70) as the second set of points.
Now, we can use the formula, 70-60 is for the top of the fraction (10)
We can do 4-6 to find the bottom, which is (-2)
Now, if we add the fraction back we get -> 10/-2 which is -5 for slope!
To find out the y intercept, it in simple words is "What is y when x is 0?".
We can do that by using the slope intercept formula:
.
Once we insert our slope which is -2 we get: 
We can now substitute a point, lets use (6,60) so we can find out b.
We now get the equation:
.
If we solve for that we get 90!
Once we input that, we get, 
Now we put in x as 0 and we get our y intercept as 90!
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