Working on my M.B.A. in finance from 1981 to 1984, I would close my office door at Frito-Lay in Dallas at 5 p.m., travel up I-35 (always under construction!) toward Denton, stop at a Braum's for a burger or, if I was in a hurry, at the gas station mini-mart for a bag of Lay's and a soft drink, and spend the evening in class.