请教GWD 5-29答案有问题？

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Q29:

Leo can buy a certain computer for p₁ dollars in State A, where the sales tax is t₁ percent, or he can buy the same computer for p₂ dollars in State B, where the sales tax is t₂ percent.  Is the total cost of the computer greater in State A than in State B?

(1)     t₁ > t₂

(2)     p₁t₁ > p₂t₂                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

 

答案为E。 我认为是C

 

p1(1+t1%)-p2(1+t2%)>0

 

[100(p1-p2)+(t1p1-t2p2)]/100>0

 

(p1-p2)+ (t1p1-t2p2)/100>0

 

条件2 p₁t₁ > p₂t₂ ==> (t1p1-t2p2)/100>0

 

条件1 t₁ > t_2 结合 条件 2 p₁t₁ > p₂t_{2    ＝＝＝》p1>=p2====> p1-p2>=0}

 

请大家帮我看看！谢谢！

moderation

t₁ > t_2 结合 条件 2 p₁t₁ > p₂t_{2    ＝＝＝》p1>=p2}

_{这个推导是不正确的.}