No calculations approach:If t#0, is r greater than zero?
(1) rt = 12
(2) r + t = 7
St1: Both r and t could be positive or both r and t could be negative. Not Suff
St2: Both r and t could be positive or either of r and t could be negative. Not Suff
1+2 --> common possibility is both r and t are positive. So r is positive i.e. greater than 0.
Ans:C
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