Answer:
a) 1/27
b) 16
c) 1/8
Step-by-step explanation:
a) 
One of the properties of the exponents tells us that when we have a negative exponent we can express it in terms of its positive exponent by turning it into the denominator (and changing its sign), so we would have:

And now, solving for x = 9 we have:

b) 
This is already a positive rational exponent so we are just going to substitute the value of y = 8 into the expression

c) 
Using the same property we used in a) we have:

And now, solving for z = 16 we have:

Answer:$80
Step-by-step explanation:
Let +n+ = number of bottles of cranberry juice needed
+2n+ = number of bottles of ginger ale needed
---------------------------
+3.2n+%2B+.9%2A%28+2n+%29+=+20+
+3.2n+%2B+1.8n+=+20+
+32n+%2B+18n+=+200+
+50n+=+200+
+n+=+4+
and
+2n+=+8+
----------------
The most bottles of cranberry juice is 4
The cactus one I think is 0.875