He tapped his temple. Then he tapped her notebook.
"The black box is only dark until you understand the light that goes in." aspen plus tutorial
"No," she said quietly. "Look. You set the distillate rate to 45 kmol/hr, but the bottoms composition spec is 99% Toluene. The mass balance doesn't close. The machine is telling you you're asking for a unicorn." He tapped his temple