SOLUTION: The variable Z is directly proportional to X, and inversely proportional to Y. When X is 12 and Y is 4, Z has the value 57. What is the value of Z when X = 18, and Y = 10 Th

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Question 981813: The variable Z is directly proportional to X, and inversely proportional to Y. When X is 12 and Y is 4, Z has the value 57.
What is the value of Z when X = 18, and Y = 10
This is what I've tried
z=kx/y
57=k*12/4=3k
k=171
z=171*18/10
z=307.8

Answer by josgarithmetic(39628)   (Show Source): You can put this solution on YOUR website!
Your first sentence:

Find a formula for k.


Your second sentence indicates:




The formula for Z is this:

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