PEABODY — Fourteen teens from across the North Shore pitched their business ideas Saturday at the Northshore Mall. The student CEOs, all between the ages of 13 and 18, are members of the Young Entrepreneurs Academy, a 25-week program hosted through the Peabody Area Chamber of Commerce designed to turn middle- and high-school students into business leaders. On Saturday, the students presented their inventions and innovations in a trade show format.