Brain Teasers
Circular System?
Given that:
a + b = 12
c + d = 7
b-c = 2
a-d = 3
Find (a-b) + (c - d).
a + b = 12
c + d = 7
b-c = 2
a-d = 3
Find (a-b) + (c - d).
Hint
It doesn't hurt to "regroup".Answer
The answer is 1. If you tried to get each letter individually, you'd probably go in circles. Instead, notice that (a-b) + (c-d) = (a+c) - (b+d).Also, (a+c) = [(a+b) - (b-c)], and (b+d) = [(a+b) - (a-d)], so:
(a+c) - (b+d)
= [(a+b) - (b-c)] - [(a+b) - (a-d)]
= [(12 - 2)] - [(12 - 3)]
= 10 - 9
= 1
or
(a-b) + (c-d)
= (a-d) - (b-c)
= 3 - 2
= 1
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Comments
Pfft! If one tries to get a value for each variable, one would most definitely twist onesself into the ground. It takes four INDEPENDENT statements to fix the value of four variables. (The four statements are not independent, because the difference of the first two sums is equal to the sum of the last two differences.) You are trying to TRICK us with excess info.
that was easy....i tuk the ryt steps to begin wid n came up wid d ans in 5 sec...woaahhhh
I just took wild guesses till I got the variables right. it wasn't all that hard, but your way is much simpler. fun teaser!
this was easy i just took my guess for a -d and got it all right lol.
Wow, that was a lot of math in your answer for such a simple problem. I just subtracted the third equation from the fourth to get 3 - 2 = 1.
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