SOLUTION: Solve for x and y, given: 25^x = 125 * 5^y (4^x) * (8^-y)=1

The system


25^x = 125 * 5^y    (1)
(4^x) * (8^-y)=1    (2)


is equivalent to


 =     (1')
 =      (2')


Which in turn is equivalent to

2x = 3 + y           (1'')
2x - 3y = 0.         (2'')


============>

2x -  y = 3
2x - 3y = 0
------------------------Subtract to get

     -y - (-3y) = 3  ====>  -y + 3y = 3  ====>  2y = 3  ====>  y = 


====>  2x =  =   ====>  x = .


Answer.  x = ,  y = .