SOLUTION: I am lost can you help me with this problem? Z varies directly as x and inversely as y. If z=123 when x=6 and y=6, find z if x=7 and y=8.

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Question 1059054: I am lost can you help me with this problem?
Z varies directly as x and inversely as y. If z=123 when x=6 and y=6, find z if x=7 and y=8.
Found 3 solutions by stanbon, josmiceli, MathTherapy:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Z varies directly as x and inversely as y.
Z = k*x/y
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Solve for "k" using "If z=123 when x=6 and y=6"
123 = k*6/6
k = 123
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Equation::
Z = 123*x/y
------
Find z if x=7 and y=8.
Ans: Z = 123*7/8 = 138.375
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Cheers,
Stan H.
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Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+z+=+k%5B1%5D%2Ax+
+z+=+k%5B2%5D%2A%281%2Fy%29+
---------------------
+k%5B1%5D+ and +k%5B2%5D+ are constants
of proportionality
---------------------
given:
+123+=+k%5B1%5D%2A6+
+k%5B1%5D+=+20.5+
and
+123+=+k%5B2%5D%2A%281%2F6%29+
+k%5B2%5D+=+738+
-----------------------
+x=7+
+z+=+k%5B1%5D%2A7+
+z+=+20.5%2A7+
+z+=+143.5+
----------------------
+y+=+8+
+z+=+k%5B2%5D%2A%281%2F8%29+
+z+=+738%2A%281%2F8%29+
+z+=+92.25+
----------------------

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
I am lost can you help me with this problem?
Z varies directly as x and inversely as y. If z=123 when x=6 and y=6, find z if x=7 and y=8.
Z+=+kx%2Fy

123+=+k%286%29%2F6 ------- Substituting 123 for Z (not z), 6 for x, and 6 for y

123 = k



Z+=+kx%2Fy

Z+=+123%287%29%2F8 ------- Substituting 123 for k, 7 for x, and 8 for y