m+z

[shibal]

is m+z>0?
a. m-3z>0
b. 4z-m>0

oa c

[mike22629]

A.) m > 3z

z could be negative and bigger than m
Ins.

B.) 4z > m

m could be negative and bigger than z
Ins.

Together:

Add inequalities:

m - 3z > 0
+(4z - m) > 0

z > 0

Since statement A says that m > 3z, we know that m must be positive as well. If they are both positive, then m + z > 0 MUST be true

C.

P.S. You can only add inequalities together. DO NOT SUBTRACT THEM!