A 75-year-old Main Line woman has admitted causing a hit-and-run one year ago that seriously injured a teenage bicyclist. Suzanne Lammers of Villanova pleaded guilty Tuesday to leaving the scene of an accident involving serious injury. It’s a felony with a minimum sentence of 90 days in jail. Court documents say the incident happened in July of last year on New Gulph Road near Morris Avenue in Bryn Mawr. Her Volvo station wagon struck Andrew Mallee of Bryn Mawr and kept on going. He was 13 years old at the time. Doctors at Children’s Hospital of Philadelphia treated him for a broken leg and head injuries, and he has a hearing loss in one ear. Montgomery County Judge William Carpenter postponed sentencing so the courts can complete an investigation and an evaluation to determine whether she qualifies for house arrest.