need help with a question from math destroyer.

[skim1988]

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While touring through Europe, Alfred finds that $1 is equal to 7 drachmas, and that 5 drachmas is equal to 3 quilos. What is the ratio of dollars to quilos?

($1/7drachmas)(5drachmas/3quilos)= 5dollars/21quilos

therefore, shouldn't the ratio of dollars to quilos be 5/21? however the answer that they provide isn't 5/21 but 21/5.

Is there something i did wrong or is this just a mistake made by the author?

thanks!

 

[BerrF12]

So for this problem you should set it up like this:

$1= 7d
3Q=5d --- d=3Q/5

Since you are trying to find $/Q, plug in the value for d that includes Q (3Q/5) and you get 21/5--- 1$= 21/5Q

Hope that helps. I always try to remember that you need to isolate the variables for what you want to solve and then plug them in.

 

[skim1988]

thank you