Answer:
t+4, t≠8
Step-by-step explanation:

The value of t must not be one that makes the denominator zero, hence must not be 8.
 
        
             
        
        
        
The answer is for the value of y-coordinate is -5
        
                    
             
        
        
        

 is a right triangle with base length 1 and height 8, so the area of 

 is 

.
The average value of 

 over 

 is given by the ratio

The denominator is just the area of 

, which we already know. The average value is then simplified to

In the 

-plane, we can describe the region 

 as all points 

 that lie between the lines 

 and 

 (the lines which coincide with the triangle's base and hypotenuse, respectively), taking 

. So, the integral is given by, and evaluates to,



 
 
        
             
        
        
        
5:9 is just 5/9
Hope this helps!