∵X+ (X-3)/7 < 0 ;
X+ (X-3)/7 ≤ 0 ;
X+ (X-3)/7 < 1 .
∴ X+ (X-3)/7 < 0
解不等式 X+ (X-3)/7 < 0
7 X + X -3 < 0
8X < 3
X < 3/8