Final answer:
The posted speed limit on Massachusetts highways under ideal driving conditions is typically 65 miles per hour (about 105 kilometers per hour).
Step-by-step explanation:
The posted speed limit on Massachusetts highways under ideal driving conditions is typically 65 miles per hour (about 105 kilometers per hour). However, it is important to note that speed limits can vary depending on the specific highway and location within Massachusetts. Drivers should always pay attention to the posted signs and adjust their speed accordingly.