I'm looking to learn all the basic math now, because now I'm an adult math looks much more interesting and easier than ever!
As I saw no exact answer for my doubt here on Math SE I resolved to ask this question, which is about the rule of three.
For example, a teacher gave me this problem for me and I quickly resolved it using the rule of three: "3 Castaways had food enough for 12 days. One (crazy) of them jumped in attempt to reach firm ground by swimming. Without one of them, how long the food will last? (something like this, I got the problem in portuguese, so I translated it my way)"
Ok. So what I made is:
3 castaways = 12 days
2 castaways = X
X = (12 * 3) / 2
X = 18
Now, what I wanna know is whether someone can give me a better explanation on why multiplying the number of days (12) by total number of castaways (3), then dividing it by the current number of castaways (2), will result the amount of days the food will last, in the end.
I mean, maybe I'm not knowing how to express myself more clearly, but that's it, I would like to understand the process in a more in depth manner, since this is the only way I can remember math for a long time, because currently I'm like: Ok, I can solve all these problems using the rule of three, but what exactly is going on behind the scenes? What makes this process function?
Thanks, I'm eager to see your answer.