Is m + z > 0 - ALGEBRAIC FORM

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Is m + z > 0 - ALGEBRAIC FORM

by venmic » Sat Jul 30, 2011 8:56 am
Is m + z > 0
(1) m - 3z > 0
(2) 4z - m > 0

I know this can be solved using numbers and I can do that

I need to know how to solve it algebraically ONLY

Appreciate your help

C
Source: — Data Sufficiency |

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by MarkMeier20 » Sat Jul 30, 2011 12:16 pm
Is m + z > 0
(1) m - 3z > 0
(2) 4z - m > 0
(1): m-3z>0 is equivalent to m+z>4z. Since we don't have any information about whether z is positive or negative, we can't conclude tan m+z>0
-> Insufficient

(2) 4z-m>0 is equivalent to m+z<5z. Since we don't have any information about whether z is positive or negative, we can't conclude tan m+z>0
-> Insufficient

(1)+(2):
If we add both equations, we get z>0. Since m-3z>0 is equivalent to m+z>4z and z>0 m+z>4z>0, Therefore C is the correct answer.