... should be, x-1, x-2, x-3, x-4, x-5 So, 38+x+x-1+x-2+x-3+x-4+x-5 =90 6x=67 x=67/6>11 32 Let attend fee be x, number of person be y: Form 1, (x-0.75)(y+100)=xy 100x-0.75y-75=0 From 2, (x+1.5)(y-100)=xy ... to know what is 20(y-x) For 1, we knew that 20(2y-x)=2400, insufficient to find y-x For 2, we knew that 20(y+2-x)=440, we can get 20(y-x)=400 It's sufficient Answer is B 29 For 1, country A can ... But this fact by itself does not tell us the order of the ratios In other words, is it - - or - - or - - 7, etc? We know, however, that the factor of is accounted for in the first year So we...