SOLUTION: if c varies directly as d and d varies directly as e, and when c=4 when e=12,find c when e=3

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Question 1105893: if c varies directly as d and d varies directly as e, and when c=4 when e=12,find c when e=3
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
I'll choose the variation constants to be k and r.

system%28c=kd%2Cand%2Cd=re%29

Substitute.
c=k%28re%29
c=%28kr%29e

We could really use just one single variable for kr.
Let K=kr.

Now highlight%28c=Ke%29.


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when c=4 when e=12,find c when e=3
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4=K%2A12

K=4%2F12
K=1%2F3

Model for the problem description is highlight%28c=%281%2F3%29e%29.

Let e=3.
c=%281%2F3%29%2A3
highlight_green%28c=1%29