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## Comment on

2 Equations with 2 Unknowns## Hi Brent, could you offer

Is rst = 1 ?

(1) rs = 1

(2) st = 1

It's clear to me why either statement alone is insufficient.

However, when combining them, I substituted the value or r from statement 1 (r = 1/s) into statement 2... essentially, I got both s and t in terms of r, that is, s = 1/r and t = r.

This makes the product rst = (r)(1/r)(r) = r.

This led me to picking E as the answer. Is this valid? All solutions of this question point towards creating tables with counter examples.

## Question link: https:/

Question link: https://gmatclub.com/forum/is-rst-90398.html

Your solution is perfectly valid.

However, once you conclude that rst = r, it's important that you confirm that r may or may not equal 1.

If it's the case that r MUST equal 1, then the combined statements are sufficient.

If it's the case that r can be ANY value, then the combined statements are not sufficient.

## Hi Brent,

Please do you have any advice on how to improve speed? I usually can solve most problems but the harder ones I solve over 2 minutes. :(

## Here are two articles that

Here are two articles that might help:

- https://www.gmatprepnow.com/articles/dealing-gmats-time-constraints-%E2%...

- https://www.gmatprepnow.com/articles/dealing-gmats-time-constraints-%E2%...

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