Given :
The foci of hyperbola are (8,0) and (-8,0) .
The difference of the focal radii = 6.
To Find :
The equation of the hyperbola.
Solution :
We know, distance between foci is given by :
2c = 8 - (-8) 
c = 8
Also, difference between the foci or focal distance is given by :
2a = 6
a = 3
Now, we know for hyperbola :

General equation of hyperbola is :

Hence, this is the required solution.
 
        
             
        
        
        
-2(5y-20) - 5y = -5
-10y + 40 - 5y = -5
-15y + 40 = -5
-15y = -45, y = 3
x = 5(3) - 20
x = 15 - 20, x = -5
Solution: x = -5, y = 3... or (-5,3)
        
             
        
        
        
5:2:11=15:6:33
Multiply by 6/2=3
        
             
        
        
        
13. Because it can't be divided by a whole number except 1 and itself. 14 can be Divided by 2. 21 and 33 can be divided by 3 making them composite or divisible by more than just 1 and itself :)
        
             
        
        
        
4 pieces  of pipe,
4/3 yd long
25/6 yd long
5 pieces same length.
(25/6)/5 = 5/6 yd  is the length of each piece of woods.