I think the best way is to plug numbers in and check, best way to do it. They need some getting use to.

for statement (1) I tried:
m-3(z) >0

7-3(2)>0, which makes this statement true....Plugging back into m+z>0? you get 7+2, which says answers "Yes"....But the main error with plugging numbers is that you can usually have more than one answer.

So pick 2 different numbers making sure the statement still stays true; try, 5-3(- 8 ) > 0 Which makes this statement true, but plugging back into the questions you get 5+-8 > 0 Which answers "NO."

The same problem applies for both statements, there are multiple ways to make the statements true, but make the question answer be "no" or "Yes."

Hope this helped,
Aj.

(1) m-3z>0 --> m>3z --> insuff

(2) 4z-m>0 --> insuff

(1) + (2) --> m - 3z + 4z - m > 0 --> z>0
(1) m>3z
-> m>0
--> m+z >0
--> C
What is OA?

my answer is C.

adding statement 1 and 2 we get Z>0 -------------------i

statement 1 says m- 3Z>0 which mean m>3Z -------------------ii

that means m>0

hence m+Z>0

Thanks everyone for the solution.

OA is C.