The court rules (
Rule 4006) explain, "Answers to interrogatories shall be in writing and verified. The answers shall be inserted in the spaces provided in the interrogatories. If there is insufficient space to answer an interrogatory, the remainder of the answer shall follow on a supplemental sheet."
You can ask the party that served you if they can provide a copy of the interrogatories on disk, so that you can insert your answers without space being an issue. I don't know about Pennsylvania, but in other parts of the country that's commonly done (and is a lot easier than retyping). If they want to adhere to the letter of the rule, use the attachments as described in the rule.