S-(C+T)

Problem Solving — algebra and arithmetic (GMAT Focus Edition)
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S-(C+T)

by AJWILL » Wed Aug 08, 2012 11:18 am
Grocery store's profit equals sales minus the cost and taxes. By what percent did the grocery store's profit changed on July 25,2005 When sales, cost, and taxes all increased?

(1) Grocery store's sales increased by 5 percent on july 25,2005.

(2) Grocery store's cost and taxes increased by 25 percent on July 25,2005.

[spoiler]Clearly A,D,B are OUT..

this is what i did S-sales, C-Cost, T-Taxes
combining. [S1.05-(C+T)1.20] - [S-(C+T)]/S-(C+T)
realising that taking S-(C+T) common from the numerator, we will get the final value!! and marked c[/spoiler]
HOWEVER answer is [spoiler]E!![/spoiler]
please explain what did i do wrong
Source: — Quantitative Reasoning |

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by eagleeye » Wed Aug 08, 2012 11:38 am
AJWILL wrote:Grocery store's profit equals sales minus the cost and taxes. By what percent did the grocery store's profit changed on July 25,2005 When sales, cost, and taxes all increased?

(1) Grocery store's sales increased by 5 percent on july 25,2005.

(2) Grocery store's cost and taxes increased by 25 percent on July 25,2005.

[spoiler]Clearly A,D,B are OUT..

this is what i did S-sales, C-Cost, T-Taxes
combining. [S1.05-(C+T)1.20] - [S-(C+T)]/S-(C+T)
realising that taking S-(C+T) common from the numerator, we will get the final value!! and marked c[/spoiler]
HOWEVER answer is [spoiler]E!![/spoiler]
please explain what did i do wrong
[spoiler]S-(C+T)is not common to all terms, you cannot isolate it from the first term of the numerator as you wrote. Hence E is correct.[/spoiler]