<p>If a, b, c, and f are four nonzero numbers, then all of the following proportions are equivalent EXCEPT:</p>
<p>(a) a/f = b/c
(b) f/c = b/a
(c) c/a = f/b
(d) a/c = b/f
(e) af/bc = 1/1</p>
<p>I don't even know where to start! By the way, this is #19 of Section 2 of the 6th practice test of the BB (2nd edition).</p>
<p>Thanks!</p>
<p>i think the answer is c. if you look at the proportions and you play around by changing the c is the only one that doesn’t make sense. it might also help if u give each variable a value.</p>
<p>The answer is A.
I hate the wording of this problem.
My first instinct was to plug numbers in. Then I realized I’d HAVE to come up with specific numbers for the proportions to work.
And that would take too long…</p>
<p>SO.
Cross multiply.
It’s A because if you cross multiply every other answer choice, you get bc = af.
But on A, you get bf = ac.</p>
<p>The answer is (a). If you cross multiply answer choices (b) - (e), you find that af=bc. Answer (a) results in ac=fb. Thus, answer (a) is not equivalent to the other answer choices.</p>
<p>I wrote my response while Mikeypz ^^ wrote his</p>
<p>Tag-teamed. </p>
<p><em>fistbump</em></p>
<p>Thanks! You guys rock.</p>