"It’s No. 446," Alyosha sighed. "The 'Reshebnik' (solution guide) in my head is broken."

"Forty-two minutes!" he shouted. "They meet in forty-two minutes."

Suddenly, the abstract numbers turned into a story. Alyosha saw the steam from the engines. He understood that their speeds added up. With a quick scribble, he divided the total distance by their combined speed.

"Need a hand?" his older sister, Katya, asked, leaning against the doorframe.