At a certain bakery, each roll costs r cents and each doughnut costs d cents. If Alfredo bought rolls and doughnuts at the bakery, how many cents did he pay for each roll?
Stat1: Alfredo paid $5.00 for 8 rolls and 6 doughnuts
It means, 8*r + 6*d = 500, or, 4*r + 3*d = 250, now, 4*r = 160 or 40 and 3*d= 90 or 210 respectively.
Not sufficient.Stat2: Alfredo would have paid $ 10.00 if he had bought 16 rolls and 12 doughnuts
It means, 16*r + 12*d = 1000, or, 4*r + 3*d = 250. It is same like statement 1.
Not sufficient.Combining 1 and 2, Still we have 1 equation and 2 probable value of r.
Not sufficient.So, I think E.