Solving Ratio Problems with Tables Question
I am attempting to enhance my (rudimentary) grasp of mathematics. It's a subject that I, sincerely, have an extremely difficult time understanding. I cannot stress enough just how frustrating the subject is. I'm only adding this prelude to my question because I've found that the video instructions assume a level of mathematical comprehension that I do not always possess and I suspect that is the root of my concern here.
In the snip above, you can see that the narrator has filled in the answers. I'm well into the tutoring session but I keep coming back to the same confusion - if the ratios shown are equivalent, why did he use different common numbers to alter them?
For instance, the narrator halved the given values to discern that 12 is half of 24. So half of 40 is 20. But then he divined 4 as a relevant input (somehow) to get his answer of 5. And finally, to discern the last value the narrator doubled the 24.
To the narrator, this makes obvious sense but to me... how do I know when to use half and when to use 4? How do I know when to double and when to use a 4? This seems completely arbitrary.
There must be some step that I am missing.
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