not bad. and very gmat-like, too. well done.
only one comment:
WHENEVER you talk about "cross multiplication", you should always note that this only works for equations.
after all, there isn't really a such thing as "cross multiply"; cross-multiplication is really just multiplication by both denominators.
if you're using an INEQUALITY, then this can get you into big, big trouble. unless you know the sign of the product of the denominators (which is equivalent to knowing whether the denominators have the same sign), you can't "cross multiply" because you won't know what will happen to the inequality sign.
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in sum:
if you get a PROPORTION (i.e., fraction EQUALS fraction), you can and should cross-multiply.
if you get an INEQUALITY with two fractions, unfortunately, you have to leave it in fractional form unless you know the relative signs of the denominators.
Ron has been teaching various standardized tests for 20 years.
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