is mx + ky '>' kx + my?
(1) m '>' k
(2) x '>' y

basically taking (m - k) outside as common(m-k)x - (m-k)y '>' 0To simplify, assume m - k = aTherefore, ax - ay '>' 0a(x - y) '>' 0Replace a with (m-k)(m - k)(x - y) '>' 0
(m - k)(x - y) will both be +ve or both be negative.

Stmt a) m '>' k....m-k '>' 0 ..but we dont know abt x-y...hence InsuffStmt b) x '>' y....x-y '>' 0 ..but we dont know abt m-k...hence Insuff
Together...Suff.Ans : C