Ratio can be calculated by dividing the given terms with each other. Example ratio of 2:4 is 2\4. I.each;1/2-1:2
A ratio is a simple proportion, which can be represented with a colon : or as a fraction. A simple ration may be 60 miles per hour, where each hour, you travel 60 miles, or it may be $1.69 per two liter bottle, where the ration is 1.69 over 2. 
To calculate ratios, simply find how you want the answer represented, and take the sample data and simply to that format.

Hope this helps:)
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