1. ## Confusing SAT problem

If a, b, c, and f are four nonzero numbers, then all of the following proportions are equivalent except:

The other options are permutations of this like f\c = b\a or c\a = f\b

Can someone explain why that is true? It says nonzero numbers so under certain circumstances can't I make it true? It seems that the problem doesn't describe enough for me to actually know

2. Originally Posted by Alan306090
If a, b, c, and f are four nonzero numbers, then all of the following proportions are equivalent except:

The other options are permutations of this like f\c = b\a or c\a = f\b

Can someone explain why that is true? It says nonzero numbers so under certain circumstances can't I make it true? It seems that the problem doesn't describe enough for me to actually know
1. Examine the 2 options:

$\frac fc=\frac ba~\implies~af=bc$

2. Do the same with the 2nd option and then with the first proportion.

..... AaaaaaHaa!